v1.10.0 - add 'fold' to control DST gaps and overlaps; add more docs and examples for ESP8266 and ESP32

• 1.10.0 (2022-01-18, TZDB 2021e)
  • MemoryBenchmark: Add memory consumption for ZoneSorterByName and
    ZoneSorterByOffsetAndName.
    • AVR: 180-530 bytes of flash
    • 32-bit: 120-600 bytes of flash
  • Rename internal TransitionStorage::findTransition() to
    findTransitionForSeconds() for better self-documentation.
  • Move third party SAMD21 boards to new Tier 3 (May work, but not supported)
    level.
    • I can no longer upload binaries to these boards using Arduino IDE
      1.8.19 and SparkFun SAMD Core 1.8.6.
  • Add support for fold parameter to control behavior around DST gaps
    and overlaps.
    • The semantics of the fold parameter is intended to be identical to
      Python PEP 495.
    • Add LocalTime::fold(), LocalDateTime::fold(),
      OffsetDateTime::fold(), ZonedDateTime::fold().
    • Update ExtendedZoneProcessor::getOffsetDateTime(acetime_t) to
      calculate the OffsetDateTime::fold() as an output parameter.
    • Update ExtendedZoneProcessor::getOffsetDateTime(const LocalDateTime&) to handle LocalDateTime::fold() as an input
      parameter.
    • Increases flash usage of ExtendedZoneProcessor by around 600 bytes
      on AVR, and 400-600 bytes on 32-bit processors.
  • Add toUnixSeconds64() and forUnixSeconds64() methods to
    LocalDate, LocalDateTime, OffsetDateTime, ZonedDateTime.
    • These use 64-bit int64_t integers, which allows Unix seconds to be
      used up to 2068-01-19T03:14:07Z (which is the limit of these
      various classes due to the internal use of 32-bit acetime_t).
    • These methods make it easier to interoperate with the time_t typedef
      for int64_t on the ESP8266 and ESP32 platforms.
  • Add EspTime app that shows how to integrate
    the SNTP client on the ESP8266 and ESP32 platforms with AceTime.