picoC: advanced navigation features and bugfixes

Now picoC can be used for autonomous navigation tasks. Switch to PH and modify the PathDesired object to fly wherever/however you want. The script can read sensors and decide what to do by itself (#1343).
If picoC doesn't respond on commands there was already a programmed timeout of 10s. Now the widget generates a message box to inform the user about a failed command (#1259).
Further the upper limit of the USART Baud rate is removed. This may be useful to generate patterns for WS2812 LEDs or other stuff.