merge

this brings compatibility up with SDL HEAD (5504), but maybe breaks compatibility with sdl 1.2 so please test! still has problems with keyboard input and rendered ttf textures

this supposedly makes hwengine work with sdl 1.3 past rev 5296

I changed r. Still not a perfect fix.

glswapbuffer consistency and create the window in the center (still, it doesn't work past sdl r5296)

Patch for issue #165: Portal: don't allow embedding Objects in ground (or porting them to impassable/invalid locations)

Fix endianness

Fix straight lines drawing issues