Allow users to add, remove and apply change tags using the API

Allow users to add, remove and apply change tags using the API

You can add tags at the same time as performing action=edit, as long as you
have the "applychangetags" right. Also, you can add or remove tags after
the fact from revisions and log entries using the API action=tags.

No UI is provided for either of these changes. The target audience is user
scripts, gadgets and similar tools.

Includes a new log parameter format type: "list", for a comma-separated
list of values.

Logging of change tag events is limited to those that do not accompany an
edit (i.e. those done after the fact), and is hidden from Special:Log by
default, similar to the patrol log.

Bug: T20670
Change-Id: I37275e0f73fa3127f55da0c320b892551b61ee80