Tried the module and fixed a few bugs

Hello,

I'm trying your module on a project using the latest PW. Unfortunately it didn't work out-of-the-box, because this project is using "PageTitleLanguage" field type. When the field "title" is a PageTitleLanguage field, the page title is an object and needs to be casted to string, otherwise warnings (illegal offset type) and weird display (e.g. "[object Object]" instead of group name) occur.

I don't think it's related, but there was also a problem with the UserGroupsHooks creating a fatal error when trying to edit user profile if the user wasn't in any group ($inputfield was null, and therefore $inputfield->isChanged() was not valid).