TableRelat. and AlphanumRelNN. refactored.

TableRelationship now uses filters for showing the
linked elements, and we also made the two classes
more lookalike, as a step prior to make a hierarchy
for them.
NN relationship table handlers hierarchy created.

Now we have a base table handler that contains much
of their code, and two subclasses that implement
different handlers. Had to change some fields names
in the abeille files to prevent unnecessary code.
Also updated navtableforms to its latest refactoring
version.
Changed some hardcoded strings to constant fields.
Several intertwined refactors.

Created a new handler for editable NN rels tables
which should be extended by editable handler, renamed
relationship contextual menu, moved TableFormFactory
to extNavTableForms with a new name and renamed
FonsaguaTableFormFactory.
Moved the NN rels tables classes to navtableforms.