Support alternate filtering modes for the surface #23
Description
Currently, if someone sets --resolution then the final layer shell surface is always rendered with whatever filtering mode the compositor chooses (probably linear). Introduce a flag called --filter which can be set to linear or nearest so that cronchy shaders can be rendered cronchily.
This needs Wayland protocol level support because there is no way to set the filter from the user side at the moment, which would take ages to implement so I'll look into this after all major issues are done.