Default input format selection by role

Now we can`t set default input format for particular user roles.

Example use case:
One could create 'editors' role. If there where possibility to select Full HTML by default for this role - contributed module WYSIWYG editor usage will be simplier, because user doesn`t have to select Full HTML for his postings every time. For anonymous users Full HTML should still be disabled.

Implementation:
May be we can add some field to user role configuration for selecting default input filter.
Following entries could be included: (Site wide selected), and list of enabled for this role filter formats.