Create ServoModule.

Signed-off-by: Wilbert Alberts <wilbert.alberts@gmail.com>
Refactor CmdUpdateFrequency; derive from ServoModule.

Signed-off-by: Wilbert Alberts <wilbert.alberts@gmail.com>
Refactor DigitalIn: base on ServoModule
Refactor DigitalOut: base on ServoModule
Refactor Motor: base on ServoModule.
Refactor Controller: base on ServoModule.