CMake for linux

[2bndy5]

The usage of CMake for this library follows suite with the same implementation in the RF24 repo (except the RF24_DRIVER option). Any user-adjustable defines in _RF24Meshconfig.h can be changed from CMake CLI options.

New build_linux workflow that

• cross-compiles & packages the library targeting armhf & arm64 architectures
  • packages targeting armhf & arm64 architectures will be automatically uploaded to future releases' assets
• tests the python wrapper installation (not cross-compiled though)
• tests the library examples (not the python examples though)

New build_ardiuno workflow that

• test-builds the examples
  • Note that _RF24Mesh_ExampleMaster.ino is incompatible with non-AVR boards due to the use of EEPROM.h, thus it is not tested in the workflow.
• ensures all examples' formatting meets the Arduino IDE expectations

PlatformIO improvements

• stopped excluding lib examples (just the Arduino examples). Seems that the exclude decision was done from a lack of understanding the "dependencies" feild in the library.json (could also have been a bug in the pio lib install ... cmd)
• added new workflow that tests all the Arduino examples on the teensy boards (all but the _RF24Mesh_ExampleMaster.ino of course)

---

• Additional improvements to the CI workflow scripts that limit triggers to only when relevant files are modified.
• added badges to README for all the new CI workflows stated above
• added a GPLv2 license for use with packaging the library (long overdue anyway)
• python wrapper now includes metadata recognized by pypi.org (specifically the license agreement)
• The Ncurses examples are now automatically built if libncurses5-dev installation is detected. If libncurses5-dev is not present, then the ncurses examples are not built
• fixed docs about addressListStruct. I accidentally broke this when I attempted to document the MESH_NOMASTER macro from _RF24Meshconfig.h in a previous PR
• unified the debug output functionality to depend on macros defined in _RF24config.h. This means that printf_P, PSTR, and PRIPSTR are used inside the new IF_MESH_DEBUG*() calls. This change also removed the old platform-dependent macros MESH_DEBUG_SERIAL and MESH_DEBUG_PRINTF.

[2bndy5]

self-reminder for release crusade (pending nRF24/RF24Network#176)

Arduino CI and Platform CI workflows are failing because they're using the latest stable release of RF24Network. This branch is using changes from CMake-4-Linux branch of RF24Network repo (specifically the addition of NETWORK_MULTICAST_ADDRESS macro defined sentinel value).

I have verified locally that the latest changes in CMake-4-Linux branches of both RF24Network & RF24Mesh libs compile & execute fine