Instead of passing all possible field values to the initialize()
function, pass all relevant data in a struct. With designated
initializers, it's more readable and makes code more comprehensible.
The general goal is to split Output's data in two categories - general
information about the output (e.g. edid) and mutable state (position,
mode, etc).
With this, the drm backend will be able to associate drmModeModeInfo
with Output's modes, which can be useful if there are several modes with
the same resolution and refresh rate but different flags.
Instead of creating a gammaramp object with a fixed size, make the color
device create a color transformation object that can be used to construct
arbitrary LUTs. This is needed in order to support tiled displays well
and is useful for further color management work.
If the backend needs to apply custom logic when changing the transform,
it should override Platform::applyOutputChanges(); otherwise just update
the Output's internal transform state.
AbstractOutput is not so Abstract and it's common to avoid the word
"Abstract" in class names as it doesn't contribute any new information.
It also significantly reduces the line width in some places.
