Geofencing for MozStumbler.

Updates as requested by @cpeterso.

Even better geofencing - menu option and status display.

Introduction of one way communication from the main thread to the BlockList.

Experimental geofencing indicator.

Changes as requested by @cpeterso.

Bug fixes. Final touches.
Merge pull request #390 from tamcap/better_geofencing

Add geofencing to pause scanner near customizable location (@tamcap)