1) Clean up a number of memory overwrites exposed by running Garmin

1) Clean up a number of memory overwrites exposed by running Garmin
protocol under Windows that don't show up with efence on Linux.

2) Don't cross the ident and shortnames of the waypoints.

gpsapp.c) Correct loops for D108 and D109 that are looking at zero
   terminated strings when its own doc says that the input is NOT
   zero terminated strings.  (Why am I rapidly losing faith in jeeps?)

gpsmem.c) Initialize several more waypoint fields on startup.