WIP Marble replacement

[u-an-i]

This is currently meant to be a poc.

MarbleWidget is replaced and all its methods implemented -- empty or not when called on app start.

It uses technology established in a GitHub project of mine without shading and without elevation and float calculations only for performance reasons; https://github.com/u-an-i/Globe.

The intention of the poc is to have the 3D sphere map draggable and zoomable interactable in LNM. (Flat map comes after.)

Dragging and zooming are currently not added / tested because QNetworkAccessManager downloads no tiles: I tried "every" placement of constructing QNAM and way of connecting slots to no avail.

I wanted to show this to you once the poc is finished but due to above nothing is shown, the app hangs in a loop on startup waiting for any type of response form QNAM: timeout, error or success, QNAM does nothig.

@albar965 I currently use QNAM like in \src\mapgui\mapgraphic.cpp:107.

If you find the idea of a Marble replacement compelling I would love if you can share an idea of how to get QNAM to do something.