abbreviations and camelCase

[KrisThielemans]

Currently rules for fields etc enforce starting with a small letter. This feels unnatural for abbreviations, e.g. we had a fan enum value ECGTrace but that gives

the symbol name 'ECGTrace' must be camelCased matching the format ^[a-z][a-zA-Z0-9]{0,63}$

forcing us to use ecgTrace. Not a major thing, but does feel strange.

[KrisThielemans]

related it #93 (comment). Personally, I find that this style guide should be optional.