Create FindSDL2*.cmake files; Remove PkgConfig usage
Merge pull request #1075 from dorkster/cmake

Create FindSDL2*.cmake files; Remove PkgConfig usage
Rename SDLRenderDevice to SDLSoftwareRenderDevice
Add command-line flags to README.engine
Merge pull request #1076 from dorkster/renderer

 Rename SDLRenderDevice to SDLRenderDeviceSW
Merge remote-tracking branch 'upstream/master'

Conflicts:
	CMakeLists.txt
	src/RenderDevice.h
	src/RenderDeviceList.cpp
Rename SDL2RenderDevice to SDLHardwareRenderDevice

Use this render device with `--renderer=sdl_hardware`