as it turns out, it is not possible to set pending breakpoints until
gdb has loaded as image. so add some hooks to enable adapters to trigger
the initial breakpoint syncing at the right time. do not add additional
states (say, InferiorPreparing), as it would just complicate things.

this includes:
- move the gdb ownership back to the engine (thus strip down the
  adaptors as far as possible)
- make gdb startup synchronous
- make adapter shutdown synchronous
- fix the state transitions relating to shutdown

after refactoring the trk adapter startup, the split was not necessary
any more. in fact, it seemed fairly arbitrary at this point.

each command can have only one of two legitimate responses: "error" or -
depending on the command, and thus declared via a flag - "done" or
"running".
this is way nicer than sprinkling the code with else-ifs (where elses
are sufficient) and asserts all over the place - and silently failing in
release builds.

--tty + outputcollector, working dir and environment setup make sense
only for living local debuggees.

Correctly reset state on missing Symbian gdb.
Provide "settings" options.
Reviewed-by: hjk <qtc-committer@nokia.com>

It had unclear semantics and was only used to show a statusmessage.
We do that directly now.

Clean out header.

Intergrate per-engine state tracking with the global running/stopped state.

rename GdbResultRecord into GdbResponse
merge cookie QVariant into GdbResponse
move debugMessage convienience function from individual adapters to base