v0.9.2: catch up on patches, clean up warnings

This release is primarily a bug-fix release, along with a GCC -Wall cleanup pass, based on using arduino-cli and the Catena-Arduino-Platform.

What's Changed

• Fix #191: missing return value, thx @surfermarty by @terrillmoore in #192
• Fixes from -Wall checks with Catena-Arduino-Platform by @terrillmoore in #197
• Fix #198: prepare release v0.9.2 by @terrillmoore in #199

Full Changelog: v0.9.1...v0.9.2