Polypolish v0.3.0

After a fair bit of experimenting, I've decided to pivot a bit and change this from a read mapping tool to a polishing tool. The tool was nearly doing polishing anyway, so I tried just making it a polisher, and it worked quite well. This also allowed me to greatly simplify the code.

Since it's no longer a read mapping tool, a name change was needed. Maskimap is dead, long live Polypolish!