Display graphics adapter name and memory in debug F5 info.
Reduce excessive memory usage by shadow map by requesting preserve contents (share render target and texture memory) and only creating one RT/stencil buffer instead of one per RenderFrame.
git-svn-id: http://svn.uktrainsim.com/svn/openrails/trunk@266 a9f3cfff-6c41-7446-b0ca-052bd761e6eb