Refactoring to improve readabilty and modularity (#113)

* remove unnecessary I prefix from UserFields interface

* fix implicit condition

* rename constants to masks to more accurately reflect the purpose of the enum

* rename constants to masks to more accurately reflect the purpose of the enum

* make MType Enum explicitly show the numbers, and make MType to Description consts and enums use more explicit typing

* add reverseBuffer in front of more assignments for consistency

* intermediate: make all _initfromWire operations slice from the incoming packet directly for consistency

* remove commented out code

* started implementing a cleaner solution for extracting LoRaWAN fields from buffer. all tests passed, but more work needed to develop a good solution.

* linter