Merge topic/reinitialize_instance_back to master.

Merge topic/reinitialize_instance_back to master.

Adds a rebless_instance_back method to CMOP::Class, which allows you to
rebless an object into a parent class.

Squashed commit of the following:

commit 163e33b72ad010907a64d39f7ade7ab257e6bf97
Author: Dave Rolsky <autarch@urth.org>
Date:   Mon Jan 4 14:18:35 2010 -0600

    Add deinitialized to whitelist

commit 7ae09debd63b91febc33c3395de34fb3635efdf9
Author: Dave Rolsky <autarch@urth.org>
Date:   Mon Jan 4 14:16:44 2010 -0600

    Run new code through tidy

commit 2586d8600533aa060741991a25ade044668cdbcd
Author: Jesse Luehrs <doy@tozt.net>
Date:   Sat Dec 19 16:17:07 2009 -0600

    implement rebless_instance_back