Glasgow Embedded / Glasgow - History

applet.{interface.ps2_host,sensor.mouse_ps2}: add historical docs.

Mostly deductions on the decision process behind assignment of
command numbers.

applet.interface.ps2_host: fix multiple setup/hold timing violations.

This worked with TrackPoint mostly by chance, but not with any other
devices...

applet.interface.ps2_host: improve handling of init sequences.

* Allow omitting init commands.
* Don't expect a data byte response to init command.

applet.interface.ps2_host: handle line NAK more gracefully.

applet.sensor.mouse_ps2: new applet.

Also, unflag ps2_host as preview, since it seems quite stable, and
appears to handle edge cases sufficiently well.

applet.memory.{24x,25x}: improve pinout diagrams.

We can do much better now that we have the :: formatting directive.

cli: allow replacing interact stage of every applet with a REPL.

And remove most repl subcommands (though, keep the customized ones,
and add some logic to steer people towards them, if they exist).

database.microchip.avr: add some ATmega*8P devices.