Introduce Views: A way to quickly reorient the sky-map to match the view through an instrument

This merge request improves the ability to orient the sky map to match the view through any instrument by introducing "Views"

A view is a collection of settings: the orientation of the sky map, how the orientation changes as the sky map is panned, whether it is mirrored or not, and optionally the field-of-view to set the map to.

If no views are defined, KStars introduces a set of standard / "demo" views by default. Existing views can be edited and new views can be added using the "Edit Views..." interface. They can also be re-ordered in the interface. The ordering of the views in the "Edit Views..." dialog defines the order in which views will be cycled through using the keyboard shortcuts Shift + Page Up and Shift + Page Down. Thus, you can set up the views for easily switching between naked eye / finder scope / telescope views for easy star-hopping.