Fix GUI scripts to avoid strict warnings.
Rejig GUI/SpiderMonkey interface to use less custom code, and to work
with JSOPTION_VAROBJFIX.
Add event name to GUI event handler function names (visible in the
profiler).
This was SVN commit r7769.
CGUI now represents a single 'page'. CGUIManager maintains multiple
pages and switches between them.
Split the XML files into pregame, loading, session and messagebox pages.
Added hotloading of GUI pages.
Minor GUI cleanups.
(Merge from hg 81862d33780c)
This was SVN commit r7214.
