[STATSGRASS] grass, gstat, and 3d maps

[Edzer J. Pebesma]

Thanks for the test data set. I corrected two bugs in gstat, and z-coordinate
reading now seems to work fine. Use:

  data(traz1):"trazas1",z=3, v=2; 

to specify the second attribute column.

The updated source code is in the "daily" snapshot of 2.3.7, at the
download are of http://www.gstat.org/

Best regards,
--
Edzer