Game -> Screen
README tweak
finished Game -> Screen conversion
class methods before initialize
fixed happy rectangle
draw/surface -> render
removed minor Screen cruft
updated README
Revert "finished Game -> Screen conversion"

This reverts commit ff9fc778f84047b6f5e3a360f6a8897710c42466.

Conflicts:
	spec/map_spec.rb
Revert "Game -> Screen"

This reverts commit 7ed0541716f36aaf32449fde46e7c0d191f4cfb1.
revert fix
DesktopBackend -> DesktopWindow
Revert "fixed happy rectangle"

This reverts commit b94e82c6f3b8bc05cd0dd8b440c099bd406cb5be.
improved docs
updated README
Map -> Stage