unix: Add option to only compile, and not execute code.
py, lexer: Fix parsing of raw strings (allow escaping of quote).
py: Make form-feed character a space (following C isspace).

Eg, in CPython stdlib, email/header.py has a form-feed character.
py: Fix lexer so it doesn't allow ! and ..
py, compiler: Implement compiling of relative imports.
Merge branch 'master' of github.com:micropython/micropython