1.0 - graduate to 1.0 with TZ DB version 2019c

• 1.0 (2019-10-02, TZ DB version 2019c)
  • Add initial support for GitHub actions to implement continuous integration
    using the unit tests that run under UnitHostDuino.
  • Allow NtpClock to use an existing WiFi connection. Add
    examples/HelloNtpClock/ to demonstrate this. (#24, thanks
    @denis-stepanov).
  • Fix compiler warning about duplicate FPSTR() macro for ESP32 Core
    version >=1.0.3.
  • Generate the zonedb files for the various validation/*Test integration
    tests on-demand, instead of using the zonedb files checked into
    src/ace_time/zonedb[x]. This allows us to match the version of the TZ
    Database used by AceTime to the version used by Java 11, pytz, and Hinnant
    Date, independently of the version that is generated into
    src/ace_time/zonedb[x].
  • Update src/ace_time/zonedb[x] files to TZ version 2019c.
  • Graduate to version 1.0.