* wombat init fix:
- fix change from #339 which removed reiniting of wombat
- allow reiniting of wombat if inited via init_new_window_wombat()
- don't allow if reinited directly from <head>, as happened in document import
* tests: fix tests for 'new _WBWombat -> WombatInit' change
* wombat: window.frames optimization:
- since window.frames === window, no need for separate override!
- ensure init_new_window_wombat() is called on any returned window from object proxy