Changed logic so that script aborts if the hexapod group is already initialized.  Controller could be uninitialized using the killall command, but it's safer to let someone do that manually.

Fixed from testing on the beamline (forgot to import hxp_drivers, forgot socketID arg to ErrorStringGet

Added checks for file existence when user specifies a file. Script looks in the backup dir if full path isn't specified (or file isn't in pwd).

Modified hxpPositionBackup.py so it will work work hexapods, rather than the bcda xps controller that was used for testing.