Removed a dead link
added opengl resource
Merge pull request #48 from iKlsR/master

added opengl resource
Added ASP.NET MVC Music Store link to ###ASP.NET MVC.
Merge pull request #49 from tinc2k/master

Added ASP.NET MVC Music Store link to ###ASP.NET MVC.
Added Open Data Structures to ####Algorithms & Datastructures.
Merge pull request #51 from bryanluby/master

Added Open Data Structures to ####Algorithms & Datastructures.
Added reference to some free laravel (a popular PHP framework) resources
Merge pull request #52 from mnishihan/patch-1

Added reference to some free laravel (a popular PHP framework) resources
removed non-free C++ book.
Merge pull request #53 from freesbies/patch-1

removed non-free C++ book.
Fix typo "Getting started with Grails"
Merge pull request #54 from martinmaillard/fix-typo

Fix typo "Getting started with Grails"
Updated Mixu's Node Book since the author has moved it
Merge pull request #55 from brennanpayne/patch-1

Updated Mixu's Node Book since the author has moved it
Removed "Ruby Best Practices"

This is neither a book nor free.
Merge pull request #56 from brigleb/master

Removed "Ruby Best Practices"
Update free-programming-books.md

Added an entry for the processing programming language.
Merge pull request #57 from sah2ed/master

Update free-programming-books.md
Added some books

Icon book (and heading), Joe Armstrong's thesis, Small Memory Software, Purely Functional Data Structures, OpenGL Insights