adding a ExpandField feature to MARC editor : all subfields that are empty and not...

adding a ExpandField feature to MARC editor : all subfields that are empty and not mandatory are hidden by default. a click on the tag title expand all of them. This is better imho than the previous minimizer, because :

Note that the minimize/expand by default behaviour could be changed to use the hidden property. Il let LibLime guys say what they think of this proposal, and discuss another behaviour.
Anyway, it proves that the new editor is better than the previous one as it can evolve easily ;-)

Signed-off-by: Chris Cormack <crc@liblime.com>