PHP book: Using Libsodium in PHP Projects

Archived link for SO inspiration list

fixes #1405

Merge branch 'master' of git://github.com/csrobinson86/free-programming-books into csrobinson86-master

Conflicts:
	free-programming-interactive-tutorials-en.md

jQuery fundamentals link fix

Add CS Unplugged: Computer Science without a computer

Correct minor typos

change "A" to "The" in "The Haskell School of Music" to match the title on the site.
change Django version number on "Test-Driven Web Development with Python" to 1.8. As the author notes [here](http://chimera.labs.oreilly.com/books/1234000000754/pr02.html#ftn.id619210), he updated the book for 1.8 in Spring 2015, since it's an LTS version.

Update free-programming-books-it.md

Add C# for beginners from Brackeys channel

Add RexEgg

Merge branch 'patch-1' of git://github.com/alfonso-cabrera/free-programming-books into alfonso-cabrera-patch-1

Conflicts:
	free-programming-books-tr.md

improves #1407

👍  Add MarkSheet

Merge branch 'isvaldo-patch-2' of git://github.com/isvaldo/free-programming-books into isvaldo-isvaldo-patch-2

Conflicts:
	free-programming-books-pt_BR.md

free-programming-books-zh.md

Alphabetizing 'en' checked

(~20%) Update broken links from url_checker

Move links from free books to free courses.

The 'en' option is checked since the capitalization has already been done. Leaving it unchecked might misguide those willing to contribute.

Original link is active and points to 1st edition. Website no longer has download for 2nd edition.

Attempted to find Github repos most similar to broken links. Otherwise, used Web Archive links, for the meantime.

Original Github Pages site is no longer found. Replaced the link with an updated repository of the same name/focus.

 add Lua org,Lua Tutorial, lua wikibook and lua interactive course 

42395 now yea!