Support for QQmlVMEMetaObject and QmlPropertyCache

We have to derive NodeInstanceMetaObject from QQmlVMEMetaObject
to support e. g. alias properties.
The QmlEngine uses QQmlVMEMetaObject to resolve
alias properties.
Also we have to invalidate/recreate the
QmlPropertyCache if we add dynamic properties.

Change-Id: Id52dd8b380eadeb6f74b5171168f2f70c16be118
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>