0.3 - implement COROUTINE_DELAY_MICROS(); update COROUTINE_DELAY_SECONDS()

• 0.3 (2019-08-26)
  • Update AutoBenchmark/README.md benchmark numbers.
  • Use a do-while loop COROUTINE_AWAIT() so that it is guaranteed to call
    COROUTINE_YIELD() at least once. Previously, if the condition of the
    await was already (or always) true, the while-loop caused the coroutine
    to hog the control flow without yielding.
  • Use a do-while loop in COROUTINE_DELAY() so that COROUTINE_YIELD()
    is guaranteed to be called at least once, even if the delay is 0.
  • Add COROUTINE_DELAY_MICROS(delayMicros) which is similar to the
    existing COROUTINE_DELAY(delayMillis) macro. The actual delay time may
    be inaccurate on slow processors (e.g. 16 MHz AVR processors) and become
    more accurate for faster processors (e.g. ESP32). (#9)
  • Breaking: The COROUTINE_DELAY_SECONDS(delaySeconds) macro now takes
    only one parmeter instead of 2 parameters. An external loopCounter
    variable no longer needs to be provided by the caller, which simplifies
    the API.
  • Add examples/Delay/Delay.ino program to validate the various
    COROUTINE_DELAY*() macros.
  • The sizeof(Coroutine) increases from 14 bytes to 15 bytes on an 8-bit
    processor. No change on 32-bit (still 28 bytes).