[GRASS5] d.vect merged into d.vect.cats

Hi,

today I have merged d.vect into d.vect.cats, added a few user
messages.

Please test it:
cvs up src/display/d.vect.cats
gmake5 -i src/display/d.vect.cats

The module accepts level1 and level2 (topology) vector data,
optionally you can select by category number and also
color fill the selected polygons or colorize vector lines.

We may replace the old d.vect with this new code then,
if no problems appear.

Cheers

Markus