Added Tox support (for travis testing)

(inspired by issue #116)

Interpreter class: fixed default behavior to return results

It emulates antlr's visitor behavior for a dynamic evaluation order of subtrees

Fix order of members when pickling Token

I found this while porting Token to C, essentially the value and pos_in_stream members of Token were swapped in ``__reduce__``, which means running ``pickle.loads`` and ``pickle.dumps`` would result in unpickled tokens whose value was the original's position in stream, and vice versa. In my C extension this caused a TypeError exception, but the behavior will have to be corrected in both.

Mostly improvements to memory consumption.

Added __slots__ to RulePtr and Token, resulting in significantly lower memory consumption.

As suggested by @drslump.

Ensure Tokens can be pickled correctly

Python 3.2 and 3.3 are End of Life

Allow functools partials to be used with the InlineTransformer

added UnexpectedToken to __init__ for help unit testing