Add Catena 4470 Support

• Add Catena 4470 support
• Add examples (as examples, and for CI testing)
• Fix #25 (add fHasSi1133)
• Doc and internal commentary improvements

Add MCCI Catena 4460 support

This release adds support for the MCCI Catena® 4460, a Feather Wing with the BME680 temperature/pressure/humidity/VOC sensor.

Bug fix, doc improvements

Fixed a problem with the STM32/Catena 4551 support, and modestly improved the documentation.

Bug fixes; correct errors in 4551 platform

This release fixes some problems with USB on the Catena 4551. It also corrects a number of minor errors in the platform structures, adds the M103 and M104 platforms, and adds explicit result for the SI 1113 lux sensor used on the 4551.

Add Catena 4551 and STM32L0 support

Major refactoring to add support for the Catena 4551, a Feather-compatible LoRaWAN node.

We're calling this a pre-release because we anticipate further refactoring and improvements in the next few weeks.