Contacts will be pruned when creating the editor. They can't be added with the ACL selector,
but we won't prevent them from being added through other means.
Allowed groups will be pruned on item submit.

NOTE: I didn't add "AND account_removed = 0" to facebook.php because I don't
have a clone of the addons repository. Please someone do that for me. Thanks.

Please check carefully. I tested locally on my server, but not with other
servers.

- Move Diaspora code into separate functions to make it more modular
- Create more checks for whether Diaspora connectivity has been enabled

Currently, the following seems to be the functional status:
	For a Diaspora top-level post:
		Friendica comments show up AND delete
		Diaspora comments show up AND delete for top-level owner
		Diaspora comments show up for non-owner
		Diaspora comments sometimes don't delete for non-owner
			-> Appears to be Diaspora's fault, as a "not a valid object" error shows up in the log

		Friendica likes show up, but can't unlike (Friendica doesn't even message Diaspora)
		Diaspora likes show up
		Diaspora non-owner can't unlike
			-> Same as comments, seems to be Diaspora's fault

	For a Friendica top-level post:
		Friendica comments show up AND delete
		Diaspora comments show up AND delete

		Friendica likes don't show up in Diaspora sometimes
		Friendica doesn't even message Diaspora for unlikes (sometimes?)
		Diaspora likes and unlikes work

Also: some whitespace cleanup, fix Diaspora parent DB query