Add various GUI pieces (exit button, resource counts, unit details).
Clean up implementation of button panels.
Split some content out of 'common' and into page-specific files.
Delete some obsolete content.
This was SVN commit r7337.
Giant merge from
http://svn.wildfiregames.com/hg-source/file/5fb522019d5e
Infrastructure is largely complete, gameplay is largely missing
Disabled by default; use command-line flag "-sim2"
(Second attempt at commit...)
This was SVN commit r7259.
