A class for fixes / coordinates?

[tjdodwell]

Discussion about should we produce a class for a "Coordinate". A "fix" is then an immutable coordinate with a unique str identifier.

This would allow us to define members functions which perform operations on such coordinates. For example "x.get_distance(y)" or "x.get_bearing_to(y)" these are currently being put into airtools (https://github.com/project-bluebird/airtools/pull/8), but perhaps naturally live with a geometric object on which they act.

[radka-j]

I really like this idea! I will make it part of the refactor.