Interwiki integration/Development

Perhaps a gradualist approach to interwiki integration development can work. Wikispaces and langspaces can be phased in step-by-step. Here is the proposed strategy:
 * Fix bug 11, because that's the easiest and simplest of them. Make the necessary changes to Linker.php, adding whatever hooks and function arguments are necessary to create an extension that will work. Create an interwiki page table.
 * Fix bug 3525. Add wikispace and langspace arguments to functions that default to null, and that have the current behavior when they are null. Create interwiki recentchanges and watchlist tables (maybe in an extension), to be shared interwiki. Refer to how it was done here, but do it better this time. Try to strike a balance between not bloating the core too much, but also not duplicating too much core code in the extension. Or maybe just say "screw it, we're going to implement all this interwiki functionality in the core."
 * There was also a bug for interwiki search somewhere. Not sure where that went. Anyway, do that last, because google can suffice in the meantime.