Implemented 'measures2geotiff' tool for gridded multi-band images (.AGE, .BSH and .THK). This tool is using a new 'export_geotiff' function that exports data into a multi-band GeoTIFF file based on a file list. Some of the MEaSUREs files have 60 or 70 categories that have to be stored in as many bands. Our old functionality was not able to handle that.

Had to make some modificatios to 'measures2netcdf' as well to accommodate inconsistent header information.

Went through the 'measures2csv' conversion, since I had seen some issues with generating shapefiles from the motion and deformation CSV files. Still re-working some 'rgps_grid2cell' aspects, not ready to be checked it just yet.
Merge branch 'rgps' of https://github.com/rudigens/ASF_MapReady into rgps