Add monitoring out port to paramHelpServer

This new port outputs all the parameters of type "monitor" in a flat
Bottle, so it can be used with the current version of YarpScope to plot
parameters. The output streaming port instead cannot be used with
YarpScope because the output Bottle has a nested structure.
Add pwm on monitoring output port

Also add parameter "send commands", which specifies whether the module
has to send commands to the motors. This is useful for the first tests
on the real robot, to see the commands on the scope without actually
sending them to the robot.