Change defaults

[mjhouse]

This PR will close #63 and #49

Main changes

• Changed the defaults of all flag enums to essentially truncate given values rather than default to whichever variant has a value of 0. So parsing a u8 with a value of 0b11 into a TransmitReceive enum will truncate to 1, which is the Transmit variant. Originally, this would have defaulted to Receive, which has a value of 0.
• Removed the Unknown variants from Address and SubAddress because they don't serve a purpose when parsing (the value being parsed from the message will always be 5 bits wide) and make usage confusing when the addresses are constructed by users of the library.

Other changes

• Removed derive as a default feature flag
• Added explicit example config in toml
• Added required feature flag derive for custom example
• Changed get to at
• Changed get_as to get
• Changed old unused_tuple_struct_fields lint to dead_code
• Updated examples to accommodate changes
• Improved code coverage
• Added a few missing must_use declarations on is_ methods

[github-actions]

Coverage

File	Coverage
All files	100%	✅
src/message/packets.rs	100%	✅
src/errors.rs	100%	✅
src/word/words.rs	100%	✅
src/fields.rs	100%	✅
src/message/messages.rs	100%	✅
src/word/enums.rs	100%	✅
src/flags.rs	100%	✅

Minimum allowed coverage is 95%

Generated by 🐒 cobertura-action against 8996833