1. (ui part) add clock time to pin changes sent to the ui *** THIS MAY BREAK EXISTING APPLICATIONS *** 2. (improvement) quick hack on hwuart.cpp to include U2X (double uart speed); this works with arduino, but is likely incorrect with other microcontrollers, if they do not have U2X; also, halving the prescaled clock is not what happens as described in the datasheet, which is instead to double the number of states in the receiver and transmitter state machine *** THIS IS QUICK HACK FOR ARDUINO, MAY BREAK simulavr ON OTHER MODELS *** 3. (ui part) the new class PinStop allows stopping the simulation when a pin changes value; this only requires creating an object of this class, passing the Pin and the SystemClock objects to the constructor 4. (to check) in hwuart.cpp, the transition into RX_READ_STARTBIT is immediate: if pinRx==0 is detected while in state RX_READ_STOPBIT after the tenth sample or while in state RX_WAIT_FOR_LOWEDGE, then _this_ sample is the first of RX_READ_STARTBIT, not the next one 5. (depends maybe on point 4. or can be fixed independent of solving point 4.) the new state RX_WAIT_FOR_HIGH in ui/serialrx.cpp (similar to that in hwuart.cpp) makes a line that just stays low not to begin a startbit; also: accept a byte only when the stopbit is correct (high) 6. (ui part) new class Measure to allow measuring time when writing to a port