[GRASS5] g51 topo

[Radim Blazek]

Hi,

I have commited some changes to grass51:
- should be possible compile with current MAIN branch g50 (merged release)
- vector 2D topology is available ( v.build, Vect_build() )
- d.what.vect - for 3D TIN can report z coordinate, GUI for attributes
- d.vect  - display area, topology id, directioin
- other news  are in grass51/CHANGES

Changes in vector library and modules are frequent and 
so that is not area for other developers yet. 
But in other parts  I whould welcome other developers in grass51.


Radim