[patch] textfield rendered as textarea

[Philipp Keller <philipp.keller@…>]

enhancements:

• models.py takes modelfield.editable into account (fields with editable=false are not drawn and not considered during model/instance to form transformation)
• a textfields default widget is now widgets.Textarea

bugfix:
When tranforming a model with a foreignkey field named "category" into a form with form_for_model/form_for_instance, posting that form, populating the posted data into this form and finally hitting save() on that form instance, the foreignfield won't be saved into db as in field "category" now is a unicode string, not a Category-Instance: "Invalid value: 'category' should be a <class 'icoc.extranet.models.Category'> instance, not a <type 'unicode'>".
I fixed this in mapping the column names to the db column names.
Though I'm not sure if this is at the right point of the process.

I ensured all the tests succeed.

[Philipp Keller <philipp.keller@…>]

• modelfield.editable already handled by Ticket 3247
• foreignkey-bugfix already handled by Ticket 3257
• textfield rendered as textarea still open, see new posted diff

[Philipp Keller <philipp.keller@…>]

Exists only the "textfield rendered as textarea" part, forget the diff above

[Adrian Holovaty]

(In [4305]) Fixed #3267 -- newforms: Changed database TextField to render as Textarea in form_for_model() forms. Thanks for the patch, Philipp Keller