Add ability to remove a contact from a subset of accounts

[boredzo]

currently, you can only remove a contact from all accounts. this stands in the way of shuffling one's contacts among one's accounts, e.g. to get around limits on buddy-list size. Adium should let you remove a contact from only some of the accounts you have the contact on.

[boredzo]

one way this could be done: add a 'delete' button (or support for the delete key) in the 'Accounts' tab of Contact Info.

[catfish_man]

I don't see this as a particularly big priority for 1.0, especially after AOL's buddy list size limit increase.

[evands]

(In [23334]) Added a (not listed) item to the groups listing in the management inspector pane of the Contact Inspector. Part of the code was actually already expectng this to exist. This allows both indication of a contact not being on the account's contact list and removal of the contact from the serverside lists of specific accounts. Fixes #1872. Fixes #6964.