QVariant does not work as they can contain custom type that corrypt the stream

Will help to clean up later.

Unfortunatelly, streaming QVariant is not a really good idea, as streaming
a custom type would fail

This mainly allows for more precise shutdown and tightens the set
of allowed transitions.

the qmlviewer is currently started from the qmljsinspector.
But this might change in the future

This updates the state diagram in debuggerplugin.cpp and
renames AdapterStart{Fail}ed to EngineStart{Fail}ed.

This replaces the (de facto) singleton engines and data handlers by classes
that are instantiated per run. The DebuggerRunControl will now create an
object of (a class derived from) DebuggerEngine that contains all the relevant
"dynamic" data.

DebuggerManager is no more. The "singleton" bits are merged into DebuggerPlugin,
whereas the data bits went to DebuggerEngine.

There is no formal notion of a "current" DebuggerEngine. However, as there's
only one DebuggerEngine at a time that has its data models connected to the
view, there's still some "de facto" notion of a "current" engine. Calling
SomeModel::setData(int role, QVariant data) with custom role is used as the
primary dispatch mechanism from the views to the "current" data models
(and the engine, as all data models know their engine).

Pass output through the RunControl instead of the DebuggerManager.

Plan is to identify make identify an IDebuggerEngine incarnation with
a RunControl.

This replaces most uses of DebuggerStartParameters by DebuggerRunControl
which is a simple RunControl with a DebuggerStartParameters member.

Plan is to move all global state to the run controls, and possibly
introduce specialized ones for core debugging etc.

This mainly reverts commit ba47987e.

Conflicts:

	src/plugins/debugger/debugger.pro
	src/plugins/debugger/debuggermanager.cpp
	src/plugins/debugger/debuggermanager.h
	src/plugins/debugger/debuggerplugin.cpp
	src/plugins/debugger/debuggerplugin.h

it's dead code

Clean out header.

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

It is replaced by a real editor in e82d6c7b.