Processing: PeriodicTimer: default constructor with interval = 0
Processing: PeriodicTimer: default constructor with interval = 0

Thus the default constructor initializes a stopped PeriodicTimer.
This should be sane behavior and having a default constructor
makes is easier to create an array of Periodc Timers.

dergraaf/xpcc,chrism333/xpcc,dergraaf/xpcc,chrism333/xpcc,dergraaf/xpcc,dergraaf/xpcc,chrism333/xpcc,chrism333/xpcc