Add SDL2 libs and headers (only win32, for now)
Apply SDL2 patch by ryan, with some adjustments to apply properly.

The fix as suggested by Jonas Kulla on the mailing list is also in.
There hasn't been any extensive testing, and it may not yet compile
on platforms other than win32.
vcproj update
Fix crash on shutdown with active SDL_gamecontroller + work around rumble effect not stopping

Tested on WinXP with wired XBox360 controller.
Update SDL2 win32 libs
vcproj fix for "Debug" config
Add a copy of FindSDL.cmake from CMake 2.8.11.2, renamed to FindSDL2.cmake

Unfortunately CMake does not yet ship a FindSDL2.cmake, so let's bundle our
own (using the existing FindSDL.cmake as a base)
Port FindSDL2.cmake to actually find SDL2 rather than SDL, and include it in CMakeLists.txt

(following instructions at http://www.cmake.org/Wiki/CMake:How_To_Find_Libraries)
Merge branch 'master' into sdl2

Conflicts:
	CMakeLists.txt
Fix compile on win32.
Add Lua function rumble() to script force feedback
Minor changes & simplifications to Lua interface. 5 new functions.

This changes all typical vector interpolation functions that get
value, time, loopType, pingPong, ease as args from the Lua state;
use unified functions for all value type occurances.
This fixes the slightly annoying problem that it was not possible to
pass a boolean true to pingPong or ease, because lua_tonumber() would
always return 0 in that case.

Also changed:
- obj_getWorldPosition() now takes optional x,y-vector

New:
- obj_getWorldPositionAndRotation() is a more efficient shortcut,
	as often both position and rotation are retrieved together,
	and the underlying matrix chain operation is rather expensive.
- entity_getEmitter()
- entity_getNumEmitters()
- setSceneColor2()
- getSceneColor2()
More new Lua functions.

- shot_getMaxSpeed()
- shot_setMaxSpeed()
- shot_getHomingness()
- shot_setHomingness()
- shot_getLifeTime()
- shot_setLifeTime()
- getScreenVirtualSize()
Make some ints floats.
Fix (harmless?) division by zero, show gamespeed in console
Oops, copypaste typo
More Lua functions; allow specifying ingredient type by ID

- avatar_setBlockBackflip()
- avatar_isBlockBackflip()
- inv_getNumItems()
- inv_getItemName()
- getIngredientDataSize()
- getIngredientDataName()
Some new Lua functions for shots. Shots will now respect the prov. unused BouncePrt property.

- shot_setDamageType()
- shot_setCheckDamageTarget()
- shot_isCheckDamageTarget()
- shot_setTrailPrt()
Implemenet proper positional audio, one issue still.

With this patch, entities can serve as a sound source whose position
updates relative to the listener. This implements the last missing
feature of my previous positional audio patch, which is moving sound sources.
Previously, all sounds were relative to the listener with the listener
centered at (0, 0, 0), and once a sound started playing, the position could
not be changed. Volume was set as an estimation of the distance to the listener.

These restrictions are now gone; OpenAL will handle the volume & panning
based on the distance.

The remaining problem is that stereo sounds are not attenuated, at all.

Lua additions:
- playSfx() takes an additional parameter now.
- entity_setStopSoundsOnDeath()
Horrible hack to attenuate stereo sources properly.

OpenAL refuses to pan stereo sources, so apparently
it needs to be done this way.