[WIP] Add LexemeViewFactory to enable adding forms.
This adds a LexemeViewFactory extending ControllerViewFactory in order
to wire the lexemeview, lexemeformsectionview and lexemeformview
together including toolbar and ToolbarViewController for the
As an intermediate solution the underlying value of the lexemeformview
widget is implemented as a Term (similar to the labelview widget) as a
workaround to provide the equals method that the ToolbarViewController
Persistence is not implemented yet. It uses a fake model instead of an
EntityChanger that always resolves the "save" promise.
Note: this is completely untested, contains a lot of TODOs, FIXMEs and
might still break in various places. Basic adding and editing of forms
should work though.