Version 1.1.1 update - better power lifecycle & debug commands

This update improves the power event handling. The app normally disables the system Auto Lock, and when the device reaches a configurable battery threshold it starts a “shutdown timer” (just re-enabling the default Playdate Auto Lock). A few cases are now handled better. Specifically:

• If you reconnect power, the “shutdown timer” is cancelled.
• Fade out all audio roughly 30 seconds before we expect to be timed out.

The amount of rain intensity change when using up/down buttons is now 1/6th of the total range each press (it used to be 1/4).

I also documented the debug commands available when connected to Playdate Simulator, and these are printed to the serial console when you start the app:

| Hello curious person!
|
| Backyard Rain Soundscape supports several development & testing commands:
|
|     i   take a screenshot and save into: images/screenshot-EPOCH.gif
|     b   toggle battery safety mode
|     d   toggle debug status overlay
|         ti: target intensity - from user input
|         i: actual intensity right now, including offset from slow variation
|         lv: light rain volume level
|         mv: medium rain volume level
|         hv: hard rain volume level
|
| In the Simulator, choose "Control Device with Simulator", then
| type one of the above keys on the computer running Simulator.
|
| Happy listening!

Enjoy!