Few books from hackershelf.com
Fix spacing, remove duplicate.
More books from hackershelf.comm
Merge remote-tracking branch 'original/master'

Conflicts:
	free-programming-books.md
Add IDL guide.

IDL is language used on astronomy, but it is now being replaced by
Python. I have added here the Getting Started with IDL.
Added python books
Remove broken link for F# Survival Guide
Add "The Art of Assembly Language Programming" book.

Adding "The Art of Assembly Language Programming" by Randall Hyde
Add a guide to IDL.
Merge pull request #94 from gabraganca/IDL

Add IDL guide.
Merge pull request #95 from jdu/patch-1

Added python books
Merge pull request #96 from simoraman/master

Remove broken link for F# Survival Guide
Merge pull request #97 from matematikaadit/patch-1

Add "The Art of Assembly Language Programming" book.
Merge pull request #89 from JIghtuse/master

Few books from hackershelf.com