[GRASS5] v.in.garmin for 5.7

A version of v.in.garmin for 5.7 is now in CVS for initial testing.

grass51/scripts/v.in.garmin/v.in.garmin

Still missing:
- route and track line attributes [*]
- support for anything other than WGS84 decimal degree input

[*] at minimum, how to do 'v.in.ascii catcol=0' with a dig_ascii file to
at least assign incrementing category numbers to the different lines? db.?? ?

Hamish