Split out common defines/types from class drivers into a seperate common class driver directory.

Make central USB Class driver dispatch headers, used for both device and host modes.

Changed to new device mode Class Driver function name prefixes to make way for similar host mode Class drivers.

Remove outdated AVRStudio project files from demos, projects, bootloaders. Fix makefiles of ClassDriver device demos.

Move new Class Driver powered demos to a new ClassDriver subdirectory, re-add old low level demos to a LowLevel subdirectory.