Finish keycodes

Rebooting works, everything works. It is a really nasty piece of code that
keyboard ISR and I needed quite some to figure out a technique to have
minimal space and code to do the conversions from ASCII and non-ASCII
keys to keycodes.

The do_keycodes routine finally gets the correct keycodes - and now there
must be routines that carry out their actions from the concepts.

Actually, Ctrl+Alt+{0,9} seems to be still reserved by qemu but I don't
care. This is something I didn't realise the last commit. Actually it might
be possible to access the qemu console somewhere around these keys. But I'm
already comfortable with the current setup. The qemu console in the qemu
"window" is kind of slow in typing what my PTY isn't.

Note that e0 sequences are not recognised as such. The e0 is discarded as
break code and the following code is taken as meaningful - what is to us. We
are not so fastidious.

I aliased 'myrun' with 'run' again as I don't want to accustom myself to new
habits. No human does.