1.5.0 - support C files; add ARDUINO=100 macro; add 'make run' target

• 1.5.0 (2022-12-08)
  • Support compiling plain *.c files in libraries and in the application.
    • The C files are assumed to be written in C11.
  • Define the -D ARDUINO=100 macro.
    • Some 3rd party libraries test for ARDUINO >= 100 to check if it's
      being compiled under Arduino.
    • Many will compile under EpoxyDuino with this macro set.
  • Add make run target which runs the binary generated by make all.
    • Useful in the vim editor where :make run will invoke the quickfix
      feature so that the editor will jump directly to the file and line
      where the AUnit assertion failure occurred.
    • Update the example for loops to invoke make -C {dir} run instead
      of running the binary directly. The vim editor can parse the output
      caused by the -C flag, and automatically generate the correct path
      to the files in the subdirectories.