Contextual menus refactored.

According to latest NavTableForms, now all
contextual menus extend the base one.
Only update contextual menu moved to NavTableForms

Other minor updates are related with the NavTableForms
menus refactoring.
Contextual menus with i18n support.

Now the custom contextual menus for fonsagua
get their texts from properties files as well.
Changed several variables to a more generic type.

Previous step from more refactoring onto NavTable-
Forms.
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.
TableFormFactory renamed and moved to navtableforms

TableFormFactory has been renamed to FormFactory
and moved to navtableforms. FonsaguaTableFormFactory
has also been renamed.
Created a new handler for editable NN rels tables

It should be extended by Editable handlers.
Layer loaded check removed from handler.

Now we do it manually before creating the handler.
We had to decided whether to pass the factory as
a parameter or to do it this way.
Renamed relationship contextual menu.

Now it has a name that is more coherent with the
naming conventions used in the handlers.
Moved the NN rels tables classes to navtableforms.
Contextual menu row number translation fixed.

The row number was not translating through the
model, which is the proper way.
Added a method for checking tables to FormFactory.

A new method for checking whether tables have
been loaded, and loading them if they haven't,
has been added to the FormFactory.
Vectorial and Alph table handlers homogeneized.

First step before refactoring them into a
hierarchy.
FormFactory transformed in a true static factory.

Now we can register a default FormFactory and it can be
accessed in a static way. Designed for making the handlers
less coupled with the actual forms.
Use the static Form Factory.

Now we register the FonsaguaFormFactory as
the default one and make all the calls through
the superclass. This step is prior to making
many of those calls in the handlers in a generic
way.
Table loading code moved to the factory.

Also removed a now redundant method from Abstract-
SubForm.
Table and layer loaded checks moved to handlers.
New hierarchy for simple table handlers.

Now we have a BaseTableHandler which is
extended by Alphanumeric and Vectorial ones.