Provides a GenServer to hold the local coordinates. This is useful for applications that are localized (e.g. telescope control) and makes possible to access the functions via the Astrex module, without supplying the local coordinates each time.

Use of the GenServer is by no means mandatory. All the functions can be accessed via the Astrex.Astro.* modules.

If the GenServer is used it is responsibility of the application to start, initialize and supervise it