Add new boards, numerous new features

This release adds support for three new boards:

• MCCI Catena 4617, a version of the 4612, which uses an IDT HS3001 instead of the Bosch BME280
• MCCI Catena 4618, a version of the 4612, which uses a Sensirion SHT31-DIS-F instead of the Bosch BME280
• MCCI Catena 4630, an air-quality variant of the 4612, which supports both TVOC and PM 2.5 measurements

It also incorporates a number of significant improvements and updates.

• #135, #178 add platform support for Catena 4617, 4618 and 4630.
• #176 add documentation on platform GUIDs.
• #170 increased size of BME680 key to allow support of recent BSEC library versions.
• #168 updates TxBuffer_t for usability.
• #158 add clock info to CatenaWingFram2k, and add API to get configured clock rate.
• #164, #165, #163 enhance logging APIs.
• #161 adds asynchronous command processing. v0.14.0.60.
• #160 add section in README.md: Adding Your Own Commands.
• #157, #153 Map SleepMode::Standby to STOP, and remove ineffective calls to __HAL_PWR_CLEAR_FLAG() in STM32 SleepForAlarm(). #150 change STM32 Sleep() to request STOP mode instead of STANDBY mode.
• #28 add lorawan join command.
• #145 Fix errors in catena_hello_lora example.
• #143 clean up a compile warning for cFramStorage::setCurrent().
• #142 add CATENA_ARDUINO_PLATFORM_VERSION to allow careful clients to #error rather than die with obscure compile problems.
• #141 add cCommandStream::getuint32().
• #140 Add example sketch for user commands.
• #138 Check ARDUINO_LORAWAN_VERSION.
• #137 Document command parser and commands.
• #136 Add system reset command.
• #125 Turn on and off HSI clock as needed if system clock is using MSI clock.
• #127 Improve，stabilize AnalogRead() API.