Collector App: Add GPS point averaging

Idea created by waveguide on Jan 9, 2014

    To improve GPS accuracy, the Collector App should have the ability to "average" GPS point data from the data stream for a specifc amount of time, rather than just capturing a single sentence from the GPS data stream. Perhaps collect the point data for 5 or 10 seconds, then use the average of these to calculate the position of the point.