"\" fix, whitespaces cleanup, tested on Ubuntu 13.04.

In README.mkd:
- removed extra "\" to make script for automatic prerequisites installation workable.
- cleaned up extra end-of-line white spaces.
- Tested everything on Ubuntu 13.04, changed "12.04" in to "13.04" in the file.

In ex-basics/ex-for.tex:
you provide an example
go run for.go
./for
but "go run" command doesn't create a "for" file. Either "./for" line should be deleted or "go build" command should be used instead.