debugger: The DebuggerEngine refactoring.

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).

src/plugins/debugger/script/scriptengine.h

@@ -30,7 +30,7 @@
 #ifndef DEBUGGER_SCRIPTENGINE_H
 #define DEBUGGER_SCRIPTENGINE_H
 
-#include "idebuggerengine.h"
+#include "debuggerengine.h"
 
 #include <QtCore/QSharedPointer>
 #include <QtCore/QScopedPointer>
@@ -52,16 +52,16 @@ class WatchData;
  * processEvents() triggered by QScriptEngine::setProcessEventsInterval().
  * Stopping is emulated by manually calling processEvents() from the debugger engine. */
 
-class ScriptEngine : public IDebuggerEngine
+class ScriptEngine : public DebuggerEngine
 {
     Q_OBJECT
 
 public:
-    ScriptEngine(DebuggerManager *manager);
+    ScriptEngine(const DebuggerStartParameters &startParameters);
     ~ScriptEngine();
 
 private:
-    // IDebuggerEngine implementation
+    // DebuggerEngine implementation
     void executeStep();
     void executeStepOut();
     void executeNext();