Implementation of category theory notions and related structures.

See http://docs.google.com/View?docid=dc7rg5cv_24ftbwjrgm for details. For the full pdf document, see http://patryshev.com/cat/doc/EasyCategoriesForProgrammers.pdf

A 5-minute slide show dedicated to scala implementation: http://docs.google.com/present/view?id=dc7rg5cv_21g5knzxdc&revision=_latest&start=0&theme=blank&cwj=true