cck 6.x-2.0-rc5

This release requires a visit to update.php to update the database.

Main bugs fixed :
- #281388 Optionwidgets: Unselect values doesn't take.
- #286457 Fix menu not being always rebuilt when needed.
- #285138 by quicksketch and yched: Allow CCK to be installed in install profiles.

Main new features :
- #282183 by chx: Nodereference - 'Checkboxes/radios' widget.
- #289138 by dopry: Add support for 'locked' fields (for module-defined fields).

Other changes :
- #273502 Add descriptions to the non-CCK form elements on the Manage fields screen.
- Fix PHP warnings when field display is set to 'hidden' and field is in a fieldgroup.
- Re-introduce '' choice for multiselect widgets (optionwidgets, noderef/userref select).
- #281449 Text: maxlength on textfield widget is 128 even when the field has no maximum length.
- Add tests for optionwidgets.
- #282175 Don't mention 'add more' button when the widget opts out of it.
- Optionwidgets: use '- None -' for 'no selection' option (like core's taxonomy.module).
- #286637 by poiu: clearer example for default value with php-code.
- #93436 Add $form parameter to content_validate.
- #277310 by fractile81: update node object by reference in content_load().
- #285771 Views integration: use the new 'float' filter handler where applicable.
- Fix PHP warnings when renaming a content type.
- #280410 Number: Fix prefix / suffix displayed when field is empty.
- #282937 Fix warnings on uninstall.
- #287540 Add index on nid in data tables, to optimize node deletion (requires update.php)
- #288578 Text: Fix max length to use utf8 length.
- #222214 by aaron, deviantintegral : support tokens for nodererf / userref paths aliases.
- #211306 by asimmonds: Fix error in D5 update with SQL strict mode.
- #292338 by mh89: Set fieldgroup.module's weight to 9 (missing for new D6 installs).
- #292463 Fieldgroup: missing update for fieldgroup table names (didn't actually break anything).
- #292855 by Tgr - Fieldgroup: missing } in query on field instance deletion.
- #292925 by greggles - Text: Fix PHP notice under some circumstances with textarea widget.
- #292675 Support d-n-d reordering of non-cck "fields" for types that have no cck fields.
- #289888 Nodereference: Fix 'full node' and 'teaser' formatters.
- Display field type human names instead of machine names on 'Manage Fields' and 'Fields' overview pages.
- #292884 Better help text for field template suggestions.
- #293163 Use FAPI validation instead of field|widget_settings($op 'validate').
(the 'validate' op is still supported, though)
- #75423 by mh89 - Text: 'size' setting for textfield widget.