Previously all of the CommandLine parsing was spread out around the
Kernel. Instead move it all into the Kernel CommandLine class, and
expose a strongly typed API for querying the state of options.
- If there is no VMWare backdoor, don't allocate memory for it.
- Remove the "unsupported" state, instead just don't instantiate.
- Move the command-line parsing from init to the driver.
- Move mouse packet reception from PS2MouseDevice to VMWareBackdoor.
