Only fields selected in plugin should be validated

[chludwig]

When using the "Save" (Edit Profile) view and not selecting fields that have validation.required = 1, they get validated and the user has no chance to save his profile.
A use case is when splitting the form data into multiple page (for example "change password", "change address", "change alias picture") and zip is empty and required. So the user gets an error message in the "change password" page telling that the zip is required even though the field is not present.

The current workaround is to create subtemplates and set required fields per page.