QtLocation map updates

[Lubomir I. Ivanov]

Here is some progress for the transition to QtLocation based map.

GIT branch:
https://github.com/neolit123/subsurface/commits/map

animated GIF preview:
https://giphy.com/gifs/3oKIP8eLtgEiM6JNEk/fullscreen

NOTES:
- tested with 5.9 and the NO_MARBLE flag
- i'm writing this map implementation, so that the widget can be used
on both desktop and mobile
- i've noticed something lawyer-esque about the ESRI plugin, so this
might be an inportant read:
https://doc.qt.io/qt-5/location-plugin-esri.html

"The Developer subscription offers a free-of-charge option for
developing and testing your applications. With this, your applications
can go to production under the following conditions:
..."

TODO:
- editing dives sites
- porting other aspects from Marble
- add context menu

lubomir
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