Fix up r108203: just loading mw.jqueryMsg in the bottom queue, then assuming its...

Fix up r108203: just loading mw.jqueryMsg in the bottom queue, then assuming its presence in mw.Message doesn't work, see CR comments.

* Moved message parsing (including $1 replacement) to Message.prototype.parser(), and let jqueryMsg override that when loaded
** Make the Message constructor public to make this possible
** Moved logic for skipping jqueryMsg when the message is simple from mw.Message to mw.jqueryMsg, where it belongs
* Remove mw.jqueryMsg from the default modules list in OutputPage. Modules that require PLURAL/GENDER should depend on mw.jqueryMsg
* TODOs
** The jqueryMsg parser is recreated for every mw.msg() call. It should probably be cached, but the only way I can think of is to add it as a member of the Map object, which is kind of weird
** Because jqueryMsg doesn't support a 'text' mode that expands PLURAL/GENDER but doesn't output HTML (leaves e.g. links alone), mw.Message.plain() and mw.Message.parse() currently behave identically. This is wrong and should be fixed, but that needs support in jqueryMsg too