Add Role select list is different when configuring the case type and adding roles to cases

Problems:

• The dropdown for adding roles to an existing case lists A to B relationships (backwards from the case-type config screen) and only for contacts of type individual (regardless of the client's contact type).
• When roles are changed it overwrites relationships which does not preserve history.
• When roles are deleted is uses a sql delete query, which does not call hooks and does not preserve history.