QmlDesigner: Don't show private imports

And refactor TextToModelMerger::setupPossibleImports

Change-Id: Ia0f1402dda59c3b5ba55adac12011251356417b2
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>
QmlDesigner: Don't add imports manually

Add Quick 1 or 2 imports to projects which are not using them can be
potentially harmful.

Change-Id: Idb4a9e1f4cd34fdb5d0e0200bc68fed334c2f80c
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@digia.com>
QmlDesigner: Use async warning

Change-Id: Ie158ea479b60394841f31b1cee72fd89f1e1ca35
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>
QmlDesigner: Don't show QtQuick import paths

Change-Id: I2789d50d0b8ce6025317b1976c87229534998a8b
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>