Merge branch 'parent-master', got filtering by categories working.

Well, mostly working. It only filters the map right now. Next up is
filtering the results list by the visible map and selected categories.
Results list is working, with some bugs

Got the results list tied to the visible markers, but there seem to be a
few bugs. Mostly when chosing categories from the list, which auto-
hides markers and re-zooms the map based on the visible markers. I'm
going to look more into this tomorrow.
Merge branch 'parent-master'
Merge branch 'master' into parent-master, closes #3