another attempt to add delete functionality in emacs

[Jameson Graef Rollins]

So, after many stabs at adding the ability to "delete" messages in
emacs [0], and the corresponding heated discussions, I'm throwing
another attempt into the fray.

I try to address the concerns that have come up in previous attempts.
In particular, I include a patch that creates a new customization
variable, notmuch-search-exclude-deleted, that will exclude any
messages with the "deleted" tag from searches.  This actually makes
"deleted" messages appear effectively deleted, which is one of the
things cworth wanted to see, and one of the reasons he kept pushing
back on previous attempts at this functionality.

Also, no tags other than "deleted" are modified.  All tags should be
orthogonal, and should be handled so.

Note: this is all about handling the "deleted" tag.  No actual
deletion of message is involved in this functionality at all.  Actual
deletion of messages should always be left entirely up to the user to
handle as they see fit.

jamie.

[0] id:"1266408746-28549-1-git-send-email-Sebastian at SSpaeth.de"
    id:"87sk8qwjlt.fsf at yoom.home.cworth.org"
    id:"1271891763-10757-1-git-send-email-hohndel at infradead.org"
    id:"1310841600-28281-1-git-send-email-anarcat at koumbit.org"