[GRASS5] New GRASS tools

[Radim Blazek]

I added some new input widgets for GRASS tools and consequently
new modules:

- v.in.ogr - import OGR vector
- r.in.gdal - import GDAL raster
- v.extract.list - extracts features currently selected in view
- v.surf.rst - interpolation
- v.surf.idw - interpolation
- v.net.nodes - creaete nodoes on network
- v.net.allocate - allocate network
- v.net.iso - cut by cost isolines
- v.net.salesman - connect by route
- v.net.steiner - connect by tree
- v.category.add - add cats

v.category is problematic because it works on all elements of layer
type, it neds new option in GRASS.

Network modules need GRASS vector map with 2 layers -
arcs and nodes. Input nodes for modules can be selected in view.

Radim