Add some more tests to parser
ast: __repr__ for for expressions
parser: Test for loops and fix for loop bug where all loops were downto
parser test: patterns
Add live test script for mac
AST: Add generic __repr__ for all AST nodes to ease debugging
livetest now depends on ast changes also
Parser test: fix whitespace
Parser test: letdef test
parser test: delete test
Make API of main module ply-agnostic. Simplify test code.
Parse: Silence PLY warnings when not starting from default state.
Tests: Order imports alphabetically (PEP8).
Lexer Tests: DRY.
Parse: Build own lexer if one is not provided.
Tests: Simplify initialization code.
Lex: Rename LexerBuilder to LexerFactory.

* Homage to Kostas Kontogiannis.
AST: Add precondition assertions for type parameter
Parse: rename some parse rules for clarity
Parse: Split simple_expr rules into several