[GRASS5] Messages and GUI

[Radim Blazek]

I have added G_messages and modified a bit G_percent, G_warning
and G_fatal_error. If GRASS_MESSAGE_FORMAT enviroment (not GRASS) variable
is set to 'gui', those functions print messages in format
suitable for parsing by GUI. gui.tcl was also modified and
displays progress bar if G_percent is used and adds icons to output box.
http://mpa.itc.it/radim/g51/messages1.png

Subject for discussion.

Question: G_warning/G_messages/G_fatal_error can print more lines,
how to tell to GUI that it is one message?

Radim