[html-formfu] many_to_many filling

[Alex Povolotsky]

defaults_from_model does only default settings.

To fill select/checkbox group/whatever else, one must add to .yml file:

db:
  model: (name-of-your-Catalyst-model)
  resultset: (name-of-proper-resultset)
  label_column: (column to put into label)

It is not documented anywhere but can be extracted from 
HTML/FormFu/Element/_Group.pm.

I'm still researching case of incorrect SQL statement for many_to_many 
model.

Alex.