Task-number: QTCREATORBUG-116

Use initializePage instead of currentPageChanged().

Move GdbAdapterState from individual adapters to GdbEngine.
Also, remove some trailing whitespace.

Make locking more fine-grained, move handling of the
No-op message into the WriterThread (basically, do not
lock dataMutex over invocation of the no-op message
as this might queue messages). Introduce a reader thread
using select()/Windows overlapped I/O, removing the need
for timers.

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

Hmm even if the cached toolchain is correct, we do a few things, maybe
I should optimize it.

Makes the project pane look nicer.

Add `Find References' of a symbol to the context menu only when the environment variable QTCREATOR_REFERENCES is defined.

Now it should finally ask to regenerate in all circumstances. (If you
are using CMake from cvs.)