qmljs: generalize language treatement

* better support qbs and similar non QtQuick qml languages
* begin to clean and migrate things from ModelManager to
  ModelManagerInterface

Change-Id: Ifa39dc1e4c568e9e21307f4913dcb5989e80420f
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
qmakeprojectmanager: check .pro file when building

A .pro file mismatch between the generated Makefile and what
should be generated was checked only at import.
Always check that (ant thus warn ifs one ends up in that situation)

Change-Id: I73436845ec82d6598ab13f446c655b644c0e6b3f
Reviewed-by: Daniel Teske <daniel.teske@digia.com>