Step to reproduce:
- change preferences once
- go back to previous page with browser button
- submit again
- exception in KnowledgeBox_baseEdit because 'form_id' is sent twice
  and is transformed by Zope into a list

also simplify some error messages

export to SXC is no longer supported in LibreOffice 4.2.4.

Any blog "front" page should shows only a short blog description not entire blog post as this makes it impossible to read / follow.

Added source_trade, source and specialise to more columns and set as searchable columns

Eg, instead of 1, 6 and 12, it was being sorted as 1, 12 and 6 users.

This is required for report including Japanese characters as Bitstream
font (the default) does not handle such characters.

This is mostly to avoid problems with proxy fields not finding their template field in default skin selection

so that we can reach the original context where FormBox is used.
also clean up modified REQUEST after rendering the target form.

- it should not hide rows when no search criterion
- set form type to form_dialog

The attempt to make sorting stable in commit
28698f35
was broken because there may be pairs of items that can't be compared,
and list.sort() relies on < transitivity.

so that portal_types.Person.getTranslatedTitle() is translated

so that the error is much more visible when the validator itself fails.

support sort_key_method in Resource.getPriceParameterDict() and rewrite Movement_getPriceCalculationOperandDict using it.

Not only for performance, but also because they would break documents
on which asComposedDocument is used.