LanguageInputWidget Generalization

This commit prepares the LanguageInputWidget to handle both annotation
and node, so it can be used as the GUI for both the LanguageInspector
and the LanguageBlockInspector that's coming up.

Cleaned up the way annotations are read into LanguageInspector and
AnnotationInspector. The attributes are kept in the Widget (without regard
to what datamodel they will serve) and are then read from the inspector.
The LinkInspector had to be adjusted slightly to accomodate a small change
in the AnnotationInspector too.

Change-Id: I17954707c00ffc4c32fbb44a6807a61760ad573c
Merge "LanguageInputWidget Generalization"