Add Unionizer

This pr addes the unionizer implementation which will take a layers-worth of features and union the 'like' features together into single geometries. There are a bunch of parameters to tweak which are explained in the conf parsing bits. I should add this info to the readme (look for a another commit to this pr). I should also note that this is not tested. I just wanted to get this pr out there for review while I write the tests and documentation. So yeah again, look for more commits.
meaning you have a line which consists of the points {{1, 1}, {1,1}, ..., {1, 1}}. So yeah i don't test for that but yeah it would mess up this algorithm. i just wonder if this is the right place to be robust to this. perhaps we need an izer called "sanitizer" that does a bunch of that stuff before getting to any other izers