Add parsing and AST support for regex-style postfix ops.

Not yet used during grammar generation.
Add plumbing for AST rewriting.
Save reference to root in all AST nodes.
Save ID->RuleAstNode map in root AST node.
Print out test pass count and total after running tests.
Implement support for Kleene star.
Update .gitignore.
Fix kleene star bugs. Add more tests. Add AST stringification.
Add support for the Kleene plus.
Move symbol 'lifting' code out of rewrite().
Support regex-style range repetition operators.
Clean up test_parse debug output.
Merge pull request #1 from jfhamlin/postfix

Support extended regular expression-style postfix operators.