Added 'and', 'or', and 'not' operators. Added tests for invalid syntax. closes gh-13
Rewrote filter tests to test full template parsing. Rewrote parser's method for getting arguments.
Benchmarking this change shows a very slight performance hit: Winner: regular Compared with next highest (negative lookahead), it's: 9.5% faster 1.11 times as fast 0.04 order(s) of magnitude faster closes gh-5