Performance improvement

• *** performance improvement:
  digital inputs, switches and buttons now set in separate threads in order to NOT wait until "slow file handling" is done before doing the next file handling to set the signals to zero or one.
  Note: still, for some reason the "overall" performance improvement is not so big.
  Added __thread_set_one/zero() and __set_one/zero().
• BUG corrected: call to self.clock.updateGuiDefs() added where missing # NOTE: self.CLOCK_PERIOD_SEC is set within this call
• BUG corrected: initialization of class variables now completely inside init()
• CLOCK_PERIOD_SEC removed as argument to some object creations as not needed (leds, digital_outputs)
• several small improvements