Added code to handle pwm using TMR1. It works on the two servo pins for now. Also added a new command to modify the pulse width of either pin.
Smalltalk commit.

* Cleaned the code a little.
* Starting to implement the morphic model. Just a couple of devices for now. Attaching and detaching works.
* Added new command to the protocol class that enables pwm on any pin (although currently only two pins are available from the firmware side).