Add 'var' in JavaScript where needed.
Fix fromLonLat in Southern hemisphere.
Add spaces in output USNG string.

Improves readability.  Valid as per FGDC-STD-011-2001 ANNEX D.1
Support zones A, B, Y and Z (poles) in fromLonLat.

Zones A, B, Y, and Z use the Universal Polar Stereographic projection.

MGRS 100km grid letters referenced from Figures 8 and 9 from:
http://earth-info.nga.mil/GandG/coordsys/grids/universal_grid_system.html

This depends on Proj4js 1.1.0 or later for the Stereographic projection.

Also, fixes UTM zone X goes to 84N not 80N.