Added a very good and complete book for Java and added iOS book
create separate md file for interactive materials
Added python books
Added Building Blocks for Theoretical Computer Science
Añadido libro de Coffeescript en español
actualizado para que funcione el hyperlink
Update free-programming-books-es.md
Update free-programming-books-bg.md

Допълнение на настоящия списък с книги за програмиране на български език.
Merge pull request #581 from haripetrov/patch-1

Update bg
Merge pull request #580 from Kikobeats/patch-1

Añadido libro de Coffeescript en español
Merge pull request #579 from colegleason/master

Added Building Blocks for Theoretical Computer Science
Merge pull request #578 from casual-passer/master

Added python books
Some alphabetizing.
Fixes typos.
Some alphabetizing.
Merge pull request #582 from jwworth/master

Some alphabetizing and typos
Added "A Guide to Python's Magic Methods"

I don't know whether this strictly meets your criteria of a "book". I'll let you decide.
16000 star in 3 month
Merge pull request #583 from sugarjig/patch-1

Added "A Guide to Python's Magic Methods"
Added "The Neophyte's Guide to Scala"