[gnome-mud] Little sample plugin

[Quim Rovira <jrovira etsetb upc es>]

I've created a very simple sample plugin that logs the received mud 
input matched agains a list of regular expressions. It still needs some 
work to be of use, but by now I've been testing it as a say/tell catcher 
with enough success. It allows multitab logging based on the matched 
regexp, and uses the same vte terminal widget used in gnome-mud.
I have no experience using the autotools, so the Makefile is actually a 
little "hardcoded", and i'll try to modify it some time.
I just thought it would be a little more complex C plugin example than 
the actual test.plugin.

P.S: Should the plugin-menu items feature be fixed or is it a waste of 
time considering the libglade port on process?

Thank you again for your great job on gnome-mud.

Quim Rovira.