* extend ListWidget to enforce classes
Previously, the undocumented *class* attribute only allowed to specify
additional classes to be set.
Especially for use within a LinkCatcher, you can now apply / enforce
only the custom classes and avoid any of the defaults being applied
depending on the link target.
This will allow to implement #1161 more gracefully.
* use setClass insted of exclamation mark syntax
update docs & fix typo in docs
661bff4f5b