Added Machine Learning Books
Added subcategory for Backbone.js and a link for 'Developing Backbone.js Applications'

Also alphabetized the subcategories under Javascript, now that there are three.
Update free-programming-books.md
Adding books about Backbone, AngularJS, GIT
Added (Programming in D) book
Fix DTrace link
Added OpenSCAD User Manual
Add "Git Magic" book.
Added Practical and Theoretical Aspects of Compiler Construction: Stanford CS143 course archives from 2012.
Added PHP: The Right Way
Merge pull request #98 from yazd/patch-1

Added (Programming in D) book
Merge pull request #99 from brunogirin/master

Added OpenSCAD User Manual
Merge pull request #101 from sanpii/git-magic

Add "Git Magic" book.
Merge pull request #102 from CrayonOfDoom/master

Added Practical and Theoretical Aspects of Compiler Construction
Merge pull request #103 from elazar/patch-1

Added PHP: The Right Way
formatting
Adds 'Developing Backbone.js Applications'
Merge pull request #104 from mdb/backbone_applications

Adds 'Developing Backbone.js Applications'
Add Android Resource from vogella
Add "PHP Internals Book".