[printers] fix bug introduced by final view refactoring:   shouldn't be escaped. Also remove some msgids which should have been removed during this refactoring

Add a hidden input:submit field in facets form (closes #1988784) <Enter> is supposed to submit the form only if there is a single input:text field. However most browsers will submit the form on <Enter> anyway if there is an input:submit field. see: http://www.w3.org/MarkUp/html-spec/html-spec_8.html#SEC8.2 Firefox 7.0.1 does not submit form on <Enter> if there is more than a input:text field and not input:submit but does it if there is an input:submit. IE 6 or Firefox 2 behave the same way.

AnyRsetView: Refactor the columns_name method and update doc. We drop the 'label_column_%s' % colidx pattern and add a clean column_label method that might be overwritten by children class to alter the way default columns headers are computed.

[facets] FacetFilterMixIn: add documention for class and generate_form There is also a small refactoring to make the code clearer. An intermediate variable is introduced and the call is reindented to make it clearer. No logic change.