QmlDesigner: Add support for .ui.qml

Change-Id: Iec0663147a9072d8332cf05ad56bcb7db0253eda
Reviewed-by: Alessandro Portale <alessandro.portale@digia.com>
TextEditor: Factory cosmetics

Pimpl, add some convenience setters.

Change-Id: I525c080179fddab6fe2bd2270505fdbf33e56be2
Reviewed-by: David Schulz <david.schulz@digia.com>
QmlJS: Distinguish between erros for ui.qml files and designer warnings

We properly distinguish between warnings in the Qt Quick Designer and
error in a .ui.qml file.

The warnings are a subset of the errors anyway.

Change-Id: Ib3b21a845436381df10863b464c975b0b39fc063
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@digia.com>