Added methods for enabling and disabling breakpoints and watchpoints,
and made debugger views update when breakpoints/watchpoints are
manipulated from Lua. Made breakpoints and watchpoints objects rather
than tables. (It’s not possible to enable/disable a breakpoint or
watchpoint from the object itself, you have to go through its owners'
debug interface.)
Exposed more device_t members for dealing with child/sibling tags and
devices. Also provided a way to get regions/shares/banks from a device
using relative tags rather than going through the memory manager with
absolute tags.
