QmlDesigner.DragTool: refactor committing of transaction

I created commitTransaction() which is called whenever we change
to the selection tool.

Task-number: QTCREATORBUG-11134

Change-Id: I1b98c8ff45864decd36f24b219f7d952e44de8fc
Reviewed-by: Marco Bubke <marco.bubke@digia.com>
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
QmlProfiler: Make sure the painter state is restored at some point.

By returning early from the method painting the binding loop markers
painter states could be left on the stack, triggering error messages
later.

Change-Id: I0b9c336e44a28feec96c506d0e3d0da291054bbd
Reviewed-by: Kai Koehne <kai.koehne@digia.com>
QmlProfiler: Make sure the different models agree on their state

Previously, the QmlProfilerSimpleModel would report a count of 1/1 when
empty while all others report 0/1. This leads to the UI waiting
forever for the "missing" data.

Task-number: QTCREATORBUG-11095
Change-Id: I165278caa5a2bece362bf869608d501d7f553c91
Reviewed-by: Kai Koehne <kai.koehne@digia.com>