Arduino library to use the watchdog timer for system reset and low power sleep.

Currently supports the following hardware:

• Arduino Uno or other ATmega328P-based boards.
• Arduino Mega or other ATmega2560- or 1280-based boards.
• Arduino Zero, Adafruit Feather M0 (ATSAMD21).
• Arduino Leonardo or other 32u4-based boards (e.g. Adafruit Feather) WITH CAVEAT: USB Serial connection is clobbered on sleep; if sketch does not require Serial comms, this is not a concern. The example sketches all print to Serial and appear frozen, but the logic does otherwise continue to run. You can restore the USB serial connection after waking up using USBDevice.attach(); and then reconnect to USB serial from the host machine.
• Partial support for Teensy 3.X and LC (watchdog, no sleep).

Adafruit Trinket and other boards using ATtiny MCUs are NOT supported.