Add Getters and Setters for Longitude / Latitude for gates

[ngoerlitz]

Hello,
would it be possible to add getters (and setters) for Latititude/Longitude pairs of a gate? This would be helpful to iterate over the stand list in order to plot gates on a map.

Thank you in advance.

Kind regards.

[atoff]

Getters would be good - not sure what the use case for setters would be for a stand? If you supply the data on init I'm not sure why you'd need to change it

[atoff]

See #9 (comment)