Add setting to control location display format

[pR0Ps]

There are a few other geocoding systems that can be used to display the current location. For example adding support for UTM was suggested to me via an email.

Instead of having DMS be in brackets beside the decimal representation, it probably makes sense to add a setting to allow users to choose their preferred system and only show that one.

[stupidly-logical]

I am interested to work on this.