add a test to check the duration of various yarp methods

[randaz81]

Some yarp methods are time critical.
We would like to check, for example, that setControlMode() lasts no more than xxx milliseconds (see also issue robotology/icub-main#234).
We have to decide if this kind of tests should be implemented separately (create new tests) or integrated in the existing tests suits (e.g. add calls to yarp::os::Time:now() inside motor-tests, controlModes etc)

[traversaro]

@randaz81 great minds think alike : #2 (comment) :D

[lornat75]

+1

Any reasons why you want to implement them separately?

BTW: robotology/icub-main#234 seems to be a glitch and it should not happen independently of the duration of setControlMode().