source/Graphics/Image/IcoFormat.cpp: use new PixelFormat.
source/Graphics/Image.cpp: update to confirm with new PixelFormat
Spectre/Graphics/PixelFormat: add PF_getNumChannels()
Spectre/Graphics/PixelFormat: Rework the enum with proper naming convention and documentation.
When writing the X11 (linux) implementation there was a problem with X11 defining a "Display" type and we also have a Display class in the engine.
So to fix that problem and minimize the risk for running into other name conflicts. We move everything from global namespace.
