Hi --

I noticed that the name included in the arduino-esp32 boards.txt section for M5Stack included hyphens in the build.board= assignment:

m5stack-core-esp32.build.board=M5Stack-Core-ESP32

When compiling under the Arduino IDE, the build.board= definition can usually be used as a macro target in a preprocessor conditional (eg. #ifdef). Unfortunately, hyphens are not valid characters in the macro name. As a result, attempting an #ifdef M5Stack-Core-ESP32 will typically result in an extra tokens at end of #ifdef directive error/warning (and I believe the compiler will interpret the statement as #ifdef M5Stack instead).

This issue could potentially be avoided if the boards.txt submission were renamed without hyphens, eg:

m5stack-core-esp32.build.board=M5Stack_Core_ESP32

At the moment this may not cause many issues, but I suspect it could result in macro collisions if M5Stack were to release other variants (eg. M5Stack-Core-zzz) in the future. Anyways, just a minor suggestion.