#1 Breakpoint support

[Fredric Echols]

The user interface (and core code) needs the ability to set and edit breakpoint addresses for:

* Addresses within each COG RAM.

* Addresses in shared RAM and ROM.

Additionally, it would be nice to have conditionals:

* Break on execute (in COG.)

* Break on read (or specific value.)

* Break on write (or specific value.)

Breakpoints could also be raised on I/O pin conditions:

* Individual pin is raised or lowered.

* Pins match a particular bit mask.