Support other pixel formats

[donotturnoff]

Through PixelFormat, we can add other pixel formats besides ARGB_8888. However, other areas of the code would need to be changed to support this.

• Replace hardcoded * 4s and / 4s
• Allow Colours to be converted to other formats
• Write optimised compositors for other formats

Other things too?

[donotturnoff]

LINEAR XRGB8888 is of particular interest

[donotturnoff]

Also of interest:

• LINEAR RGB565
• LINEAR ABGR2101010
• LINEAR XBGR2101010
• LINEAR ARGB2101010
• LINEAR XRGB2101010
• LINEAR C8
• LINEAR P010
• LINEAR NV12
• LINEAR XBGR8888
• LINEAR ABGR8888