This is a simple light-chasing demo, similar to the basic demo, but now with
the chaser and vitrine modules synchronised, which results in _much_ lower CPU
usage. 
The synchronisation may be configured using two alternative methods. A sample of
the more complex, but more complete, method is available in the 
matplc.conf.complex file. A sample of the simpler, but less powerful, method
is available in the matplc.conf.cimle file. To use one of them, simple copy
the file onto another file named matplc.conf (or use a symbolic link instead).

It also allows to stop/run the PLC with ./plc_stop and ./plc_run if the
complex configuration version is being used.

To start:
	cd demo/basic; make

To quit:
	press `Q' on the keyboard


It's controlled from the keyboard (module Kbd, kbd.c): the keys L, R and Q
on the keyboard toggle the three points `left', `right' and `quit'.

The Chaser module (chaser.c) is a primitive `light chasing' program. The
direction of movement can be changed using the `left' and `right' points;
these are notionally push-buttons, but in this demo they are controlled by
the L and R keys. The speed of the chaser can be configured with the
"delay" setting in the "Chaser" section of matplc.conf

The demo terminates when the `quit' point comes on (keyboard Q).


Buglets:
	- chaser may miss the `left' or `right' button if you press and
	  quickly release it, because it's badly written.
	- assumes a linux terminal (hard coded escape codes).

Notes:
	- kbd.c should eventually be replaced by a proper curses-based HMI thing
	- `demo' itself should be done in a generic fashion, rather than by
	  hard-coding all the modules; every program will need something to
	  start up all the modules at the beginning and shut them all down
	  at the end (perhaps giving them time to shut themselves down if
	  they want to).