[GRASS5] function return values?

[Markus Neteler]

Hi again,

while looking at the return codes of 5.0, it seems that
there no standard was followed. To improve things in
5.1 we should define some rules (for SUBMITTING) and
also update code accordingly when moving it to 5.1.

Suggestion (there will be exceptions):

error: 0
success: 1 (this allows a simple if(G_function()) test
            without comparison).

Being no expert here, I hope for comments,

 Markus