Update Hydra.ino

1. Debounce the zero-crossing detection in the ammeter code. Go back to just using one full cycle (3 zero-crossings).
2. Go back to using moving averages to smooth ammeter and pilot readings.
3. Straighten out / correct a little bit of the logic around state transitions.
4. Bring the amperage grace down to 500 mA. We now know that the previous peak reading method's inaccuracies were why Leafs were reading so much higher than expected.