Added Italian and Portuguese translations + Updated version. (#4595)

* Added Portuguese and Italian Translations.

Added Portuguese and Italian Translations of the book Python For Everybody by Dr. Charles Russell Severance

* Update free-programming-books.md

Updated the link to the latest edition.

* Update free-programming-books.md

Updated edition for the book with author and links in three places.

* Update free-programming-books.md

Added Think DSP - Digital Signal Processing in Python.

* Update free-programming-books.md

Added Think Data Structures: Algorithms and Information Retrieval in Java.

* Update free-programming-books.md

Added two new books;
Think C++: How To Think Like a Computer Scientist
Modeling and Simulation in Python

* Minor changes to adhere to Contributing.md

Thanks to @kashirash
Suggested edits to pass travis-ci and respecting markdown formatting.

free-programming-books-it.md

@@ -227,6 +227,7 @@
 * [Immersione in Python 3](http://gpiancastelli.altervista.org/dip3-it/) - Mark Pilgrim, _traduzione di: Giulio Piancastelli_ (HTML) [(PDF)](http://gpiancastelli.altervista.org/dip3-it/d/diveintopython3-it-pdf-latest.zip)
 * [La libreria di riferimento di Python](http://docs.python.it/html/lib/)
 * [Pensare da Informatico, Versione Python](http://www.python.it/doc/Howtothink/Howtothink-html-it/index.htm)
+* [Python per tutti: Esplorare dati con Python3](http://do1.dr-chuck.com/pythonlearn/IT_it/pythonlearn.pdf) - Dr. Charles Russell Severance (PDF) [(EPUB)](http://do1.dr-chuck.com/pythonlearn/IT_it/pythonlearn.epub)
 
 
 #### Django

free-programming-books-pt_PT.md

@@ -5,6 +5,7 @@
 * [Haskell](#haskell)
 * [LaTeX](#latex)
 * [Prolog](#prolog)
+* [Python](#python)
 
 
 ### C/C++
@@ -32,3 +33,8 @@
 ### Prolog
 
 * [Lógica Computacional (com Prolog)](http://www4.di.uminho.pt/~mjf/pub/LC-Prolog.pdf) - Maria João Frade (PDF)
+
+
+### Python
+
+* [Python Para Todos: Explorando Dados com Python 3](http://do1.dr-chuck.com/pythonlearn/PT_br/pythonlearn.pdf) - Dr. Charles Russell Severance (PDF) [(EPUB)](http://do1.dr-chuck.com/pythonlearn/PT_br/pythonlearn.epub)

free-programming-books.md

@@ -343,7 +343,7 @@
 * [The Design of Approximation Algorithms](http://www.designofapproxalgs.com/book.pdf) (PDF)
 * [The Great Tree List Recursion Problem](http://cslibrary.stanford.edu/109/TreeListRecursion.pdf) (PDF)
 * [The Kademlia Protocol Succinctly](https://www.syncfusion.com/ebooks/kademlia_protocol_succinctly) - Marc Clifton
-* [Think Complexity](http://greenteapress.com/complexity/) (PDF)
+* [Think Complexity](https://greenteapress.com/wp/think-complexity-2e/) - Allen B. Downey (2nd Edition) (PDF, HTML)
 
 
 #### Artificial Intelligence
@@ -858,7 +858,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [Structure and Interpretation of Computer Programs](http://sarabander.github.io/sicp/html/index.xhtml)
 * [The Black Art of Programming](http://self.gutenberg.org/wplbn0002828847-the-black-art-of-programming-by-mcilroy-mark.aspx?) - Mark McIlroy
 * [The Craft of Programming](https://kilthub.cmu.edu/articles/The_Craft_of_Programming/6610514) - John C. Reynolds
-* [Think Complexity](http://www.greenteapress.com/compmod/) - Allen B. Downey
+* [Think Complexity](https://greenteapress.com/wp/think-complexity-2e/) - - Allen B. Downey (2nd Edition) (PDF, HTML)
 
 
 #### Web Performance
@@ -1107,6 +1107,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [The Boost C++ libraries](http://theboostcpplibraries.com)
 * [The Rook's Guide to C++](http://rooksguide.org/2013/11/26/version-1-0-is-out/) (PDF)
 * [The Ultimate Question of Programming, Refactoring, and Everything](https://www.gitbook.com/book/alexastva/the-ultimate-question-of-programming-refactoring-/details)
+* [Think C++: How To Think Like a Computer Scientist](https://greenteapress.com/wp/think-c/) - Allen B. Downey (PDF)
 * [Thinking in C++, Second Edition, Vol. 1.](https://archive.org/details/TICPP2ndEdVolOne) - Bruce Eckel [(Vol. 2)](https://archive.org/details/TICPP2ndEdVolTwo)
 
 
@@ -1587,6 +1588,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [The Java EE7 Tutorial](https://docs.oracle.com/javaee/7/JEETT.pdf) - Eric Jendrock, et al (PDF)
 * [The Java Tutorials](https://docs.oracle.com/javase/tutorial/index.html)
 * [The Java Web Scraping Handbook](https://www.scrapingbee.com/java-webscraping-book) - Kevin Sahin (PDF, HTML)
+* [Think Data Structures: Algorithms and Information Retrieval in Java](https://greenteapress.com/wp/think-data-structures/) - Allen B. Downey (PDF, HTML)
 * [Think Java: How to Think Like a Computer Scientist](http://greenteapress.com/thinkapjava/) - Allen B. Downey and Chris Mayfield
 * [Welcome to Java for Python Programmers](https://runestone.academy/runestone/books/published/java4python/index.html) - Brad Miller
 * [Welcome to the Java Workshop (2006)](http://javaworkshop.sourceforge.net) - Trevor Miller
@@ -2302,7 +2304,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [How to Make Mistakes in Python](http://www.oreilly.com/programming/free/files/how-to-make-mistakes-in-python.pdf) - Mike Pirnat (PDF) (1st edition)
 * [How to Think Like a Computer Scientist: Learning with Python, Interactive Edition](http://interactivepython.org/courselib/static/thinkcspy/index.html) (3.2)
   * [How to Think Like a Computer Scientist: Learning with Python](http://www.greenteapress.com/thinkpython/thinkCSpy/) - Allen B. Downey, Jeff Elkner and Chris Meyers (2.4)
-  * [Think Python](http://www.greenteapress.com/thinkpython/) - Allen B. Downey (2.x & 3.0)
+  * [Think Python 2e](https://greenteapress.com/wp/think-python-2e/) - Allen B. Downey (2.x & 3.0)
 * [Intermediate Python](http://book.pythontips.com/en/latest/index.html#) - Muhammad Yasoob Ullah Khalid (1st edition)
 * [Introduction to Programming with Python](http://opentechschool.github.io/python-beginners/en/) (3.3)
   * [Introduction to Programming Using Python](http://python-ebook.blogspot.co.uk) - Cody Jackson (1st edition) (2.3)
@@ -2316,6 +2318,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [Lectures on scientific computing with python](https://github.com/jrjohansson/scientific-python-lectures) - J.R. Johansson (2.7)
 * [Making Games with Python & Pygame](http://inventwithpython.com/pygame/chapters/) - Al Sweigart (2.7)
 * [Math for programmers (using python)](https://akuli.github.io/math-tutorial/)
+* [Modeling and Simulation in Python](https://greenteapress.com/wp/modsimpy/) - Allen B. Downey (PDF)
 * [Modeling Creativity: Case Studies in Python](http://www.clips.ua.ac.be/sites/default/files/modeling-creativity.pdf) - Tom D. De Smedt (PDF)
 * [Natural Language Processing with Python](http://www.nltk.org/book/) (3.x)
 * [Non-Programmer's Tutorial for Python 3](https://en.wikibooks.org/wiki/Non-Programmer%27s_Tutorial_for_Python_3) - Wikibooks (3.3)
@@ -2360,7 +2363,8 @@ Kerridge (PDF) (email address *requested*, not required)
 * [The Programming Historian](http://niche-canada.org/research/niche-digital-infrastructure-project/the-programming-historian/) - William J. Turkel, Adam Crymble and Alan MacEachern
 * [The Python GTK+ 3 Tutorial](http://python-gtk-3-tutorial.readthedocs.org/en/latest/)
 * [The Standard Python Library](http://effbot.org/librarybook/) - Fredrik Lundh
-* [Think Complexity](http://greenteapress.com/complexity/) - Allen B. Downey (2nd Edition) (PDF, HTML)
+* [Think Complexity](https://greenteapress.com/wp/think-complexity-2e/) - Allen B. Downey (2nd Edition) (PDF, HTML)
+* [Think DSP - Digital Signal Processing in Python](https://greenteapress.com/wp/think-dsp/) - Allen B. Downey (PDF, HTML)
 * [Tiny Python 3.6 Notebook](https://github.com/mattharrison/Tiny-Python-3.6-Notebook) - Matt Harrison (3.6)
 * [Web2py: Complete Reference Manual, 6th Edition (pre-release)](http://web2py.com/book) (2.5 - 2.x)