#724 updated the navit logo, but forgot about the desktop icons used for Sailfish and maybe others.

* Updating navit logo for QT
* Adding navit icon to GTK GUI's windows, using the black and white version of the icon in GTK GUI for better readability
* Fixing memory leak in GTK geticon()
* Adding source svg for all variations of the logo (integrating to the repo, the svg logo catalog that was last posted in #436 (https://github.com/navit-gps/navit/issues/436#issuecomment-450587935)

Credits for logo design: redmusic27 and zintor

* fix:core:refactor polygon clipping

This commit extracts the polygon clipping into its own function to be
re used for polygon with holes clipping.

* fix:core:Clip polygons with holes prior drawing.

While this helps drawing for limited graphics like SDL or WindowsCE,
it will slightly slow down on graphics that do clipping themselves like
qt5. As this is done for polygons already, we do this for polygons with
holes as well.

Admin levels for additional countries

Add:graphics/windows: polygons with holes for windows CE

This uses the same "hand and foot" raycasting algorithm than the SDL version does since WindowsCE lacks the fancy drawing routines of better Windows.

Add:graphics/sdl: Polygon with holes support.