action bar icon for locking marker to user location now changes with
mode
added ability to read in gridfloat files
wrapped gridfloat file reader in asynctask
added some new methods
selected markers are now blue to match 'holo' theme
separated application-specific code from reusable library classes,
tried to make things more modular/extensible
fixed initialization of field class static variables in mainactivity
moved locationlistener to seperate class
DEM read from SD is implemented but runs out of memory