Fixes #161 - adds ~30x faster tokenizer.

* Splits data into 128 bytes long chunks (rounded to nearest closing parenthesis).
* Won't seek trough the whole document all the time.
Adds minor speeed optimizations to property & selector optimizers.
Skips empty removal if advanced processing is enabled.

* Since advanced processing tokenizes data we can rebuild it without empty elements.
Fixes #160 - re-runs advanced optimizations until no changes are detected.

* That's because merging adjacent selectors can lead to new optimization opportunities.
Minor style changes.