[MISC]  Fix README, cleanup.py, ast_gen, gitignore

Major changes in thinking the way the project should proceed have
resulted in changes in the README.

Realization that gitignore does not accept advanced Unix wild-cards
leads to change in git ignoring strategy of syntax_tree package.

Switched ast_gen to update the generated files when run as main script.

cleanup.py only deletes syntax_tree files if in DEV mode.
[BUGFIX, TESTS] Minor bugfixes to syntax_tree

Renamed nodes in test_syntax_tree to something more meaningful.

Fixes in py2c.syntax_tree:identifier
 - In equality, if both nodes don't have the same attribute, the
   attribute is considered equal. (NEEDS TESTS)
 - Regex (now) matches dotted names too!
[IMPLEMENT] Add Py2ASTTranslator with tests

Add a translator for translating Python code into our version of the
AST, with corresponding tests and AST definition modifications.