If an Arduino pin was used as an input (e.g. by EXRAIL) without previously configuring it, the default pullup wouldn't be set up. Now, on first call to the _read() method the pullup will be enabled.
Previously, pullups were enabled on GPIO Expander digital pins by default, even if the pin was only ever used as an output. This could lead to a spurious HIGH state being seen by external equipment before the output is initialised to LOW. To avoid this, the pin pullup is now not enabled until a configure or read operation is issued for the pin.
Alias for existing <D SERVO ...> command added as <D ANOUT ...> (since not all analogue outputs are servos). Also, <D ANIN vpin> added to display the value of an analogue input pin.
Remove virtual method hasCallback().
Optimise findDevice() method (used by read, write etc.).
Simplify Sensor handling with regard to IO Devices that support callbacks.
The range of accessory decoder addresses for the <a> command is 0-511 in line with the DCC packet contents. The turnout command previously rejected address 0; this has been changed to the same range of addresses can be used by both commands, i.e. address 0-511 and subaddress 0-3. The linear address mapping remains so that linear address 1 is addr/subaddr 1/0; i.e. the first decoder address is not accessible by linear address.
Performance enhancements in IODevice::loop() function.
Improved error handling, device is placed off line if not responding.
Improved error reporting, device shown as offline if not operational (faulty or not present).
When writing to analogue outputs pins, the digital _read() function now returns the 'busy' status of the analogue pin. Consequently, the _isBusy() function becomes superfluous and has been removed. The static IODevice::isBusy() function now calls the object's _read() function instead.
Also, limit in DFPlayer of 3 pins has been removed.
