- Add a tag field to all endpoint messages, which doubles as a
notification field
- Add a endpoint_bind_irq syscall to enable an endpoint to listen for
interrupt notifications. This mechanism needs to change.
- Add a temporary copy of the serial port code to nulldrv, and let it
take responsibility for COM2
Added the syscalls/helpers.h file to templatize common kobject syscall
operations. Also moved most syscall implementations to using
process::current() and thread::current() instead of asking the
scheduler.
