9/1999 Bill Hughes/Markus Neteler

v.extract and v.merge updated to GRASS 5
(change in vector cats management)
and moved to into main code src/mapdev/

   The Categories structure was changed between 4.2.1v21 and 5.0beta.
The change seems to have moved the *labels element out of the list
structure and replace list.num with the index to **labels.  The fix
is to change the SCS/* code to use 'cats->labels[i]' instead of
'cats->list[i].labels'  There will be breakage around 'list[i].num'
as well, and probably these can be deleted, or use 'cats->num' instead.

