Arduino Dual Channel ASCOM Focuser

The focuser is based on Arduino Nano board and ULN2003 driver board off the ebay. It supports Moonlite focuser protocol with the following improvement and limitation.
- Dual channel focuser controller by single Arduino Nano chip
- ASCOM Local Server drivers are also provided
- Using AccelStepper library, to provide speed acceleration and deacceleration, to avoid slippage. There is no noticeable slippage at highest speed. At contrast, Moonlite focuser slips even at lowest speed.
- Provide 0.125 degree temperature reading accuracy, as opposed to 0.5. It also provides compatibility mode (ie. 0.5 degree).
- Hardware controlled TempComp (Moonlite uses driver), with programmable trigger (temperature drop).
- TempComp only tracks temperature drop. When temperature goes up over hysteresis limit (which should be very rare), it will report an error.
- HALT command is implemented but it does not stop focuser right away, instead it will move some time more (depending on the speed)