Internationalization, Bugfixes, benchmarks

Implemented parsing for >1byte runes everywhere (means the entire utf8 range is open for use)

Fixed panics when using fixed-point parameters during evaluation

Fixed parsing error when parsing variables that contained underscores, such as when using used snake_case.

Fixed bugs which prevented using comparators after a clause, previously expressions like "(2 + 2) >= 4" would fail to parse

Added some benchmarks (go test -bench=.)