GRASS benchmarks

As you can compile GRASS with different compiler options (see
../INSTALL for details), here some functions for simple
benchmarking:

Using
 g.region res=X -p
with X set to a number you can use any GRASS location for these
tests. The resolution defines dependent from the boundary coordinates,
how many raster rows and cols are currently set. 

Here we go:

#Two test patterns are generated and patched:
#Generate first pattern:
 date; r.mapcalc testA="if(row()%2., row(), null())"; date

#Generate second pattern:
 date; r.mapcalc testB="if(col()%2., col(), null())"; date

#Patch it:
 date; r.patch in=testA,testB out=testpatch; date

[to be cont'ed]