[rfc] Annotation level THREE

[Nick Roberts <nick@nick.uklinux.net>]

> To follow through a discussion on gdb@ this patch adds annotation level 
> three to the GDB sources.

> Annotation level three:

> - keeps the event notifications from annotation level two
> - removes all the output markups

I don't really follow this. It looks like level three annotations will have
a lot of the annotations missing. To currently work gdb-ui.el needs:

frames-invalid
breakpoints-invalid
pre-prompt
prompt
commands
overload-choice
query
prompt-for-continue
post-prompt
source
starting
exited
signalled
signal
breakpoint
watchpoint
frame-begin
stopped
display-begin
display-end
display-number-end
array-section-begin
array-section-end
field-begin
field-end

It needn't use frames-invalid and breakpoints-invalid which are repeatedly
generated during a run and possibly other selected ones could go. However,
some appear to be essential e.g display-begin as the MI equivalent,
-display-insert, isn't implemented and I don't know how to make use of
variable objects.

Nick