logic example module

The Logic-module is an example on how to create modules that can 
interface to gpsim. 

You may examine the source to see the steps one must go through
to create a custom module. There's a lot of clutter associated 
with implementing the graphics.

The examples/ subdirectory illustrates a pic assembly file along
with a .stc file that will exercise the module. Here are the steps
on how to use it:

gpasm logic_mod.asm
gpsim -c logic_mod.stc