* MAX_SCREENHEIGHT is more or less eliminated as a limit now.
* MAX_SCREENWIDTH use further reduced, but portal engine proves extremely stubborn...
* Visplanes are now completely destroyed during a resolution change, and all planehash instances are subsequently reset by VAllocItem callbacks.

git-svn-id: http://mancubus.net/svn/hosted/eternity/trunk@2435 86ba831e-150c-0410-ab35-e06eaae15ed9
Incremental improvement to dynaseg fragment sorting lessens some issues in vapordemo, but others still remain and cannot be fixed without transitioning to a full BSP solution similar to ZDoom's.

git-svn-id: http://mancubus.net/svn/hosted/eternity/trunk@2436 86ba831e-150c-0410-ab35-e06eaae15ed9