Filter by map zoom level

[lunerfox]

I've been steadily adding locations to my files, and noticed that loading hundreds of locations tends to take upwards of 10-15 seconds for me.

I rarely need this many locations to be loaded; One solution is to bound the search by looking at the lat,long values and bounding them to return much fewer results.

This can be done automatically if somehow the search matched up with the zoom level of the map so it only returns what it can see.