Translate the image to move it to (0, 0)

refine swift interfaces

add `colorPrimaries`, `colorYCbCrMatrix` and `colorTransferFunction` …

…for `MTIVideoComposition`

alpha type assertion improvements

remove the load action assert for memoryless render targets while the…

… render target is not actually memoryless

add video export / audio record support to the example project

remove implicit member expressions for compatibility

Color space handling and documentation update (MetalPetal#246)

close MetalPetal#244

MTIVideoComposition: documentation and cleanup

fix MetalPetal#235