[GRASS5] g51 shape

[Radim Blazek]

Hi,

few updates for shapefiles:
- for areas pseudo topo is build now, instead of standard grass topo,
  it means that all areas and islands should be build without problems,
  (centroid position is not yet calculated correctly)
- category is read from dbf table

It means that it should be possible display and query shapefiles in grass
without import. Attributes may be read from original tables.

Example frmt (isles.shp):
FORMAT: shape
SHAPE: /home/radim/gdata/g51test/shp/isles
CAT_COLUMN: CAT_ID

Example DB:
isles.shp 1 isles cat_id $GISDBASE/$LOCATION/shp dbf


Radim