lex.py -> parse.py; do lexer and parser in one
parser.py: Parser now calls compiler methods instead of yielding tokens.

Parser is still more of a lexer.  Will become a parser soon.
parse.py: move has_proper_prefix to top
parse.py: Make Parser a parser :)
parse.py: Cleanup
parse.py: Close multiple blocks with same indent (e.g. p: p) properly