GDB working, some more source massaging

GDB working, some more source massaging

Big news is gdb support, you can trace, breakpoint,
resume, inspect (including eeprom addresses!).
You can't modify variables on the fly yet.
It's not very fast rignt now, but some very obvious
changes will help that a lot.

Other changes are more moving, shuffling. "simavr"
is gone, replaced by a simple "run_avr" that does
the same, but no longer has any emulation specific
code.

Signed-off-by: Michel Pollet <buserror@gmail.com>