Save cpu portion of emulation state

Signed-off-by: Josh Kilmer <srjek2@gmail.com>
Save device portion of emulation state

Signed-off-by: Josh Kilmer <srjek2@gmail.com>
Save callback portion of emulation state (all emulation state is now saved)

Signed-off-by: Josh Kilmer <srjek2@gmail.com>
Restore cpu and callback portion of emulation state

Signed-off-by: Josh Kilmer <srjek2@gmail.com>
Restore device portion of emulation state (all emulation state is now restored)

Signed-off-by: Josh Kilmer <srjek2@gmail.com>