More advanced hill shading

[anders-kiaer]

Currently hill shading in the layered map component is calculated using WebGL and direct light from a point source. This can make it easier to visually see structure/depth maps. However, since it is a single point source it tends to over expose areas facing the light, and obscure details on the non-illuminates sides.

This can be improved by using either one source with finite size, or multisource hill shading. For inspiration and literature, search for multi-directional hillshading and cartography professor Eduard Imhof (1895 – 1986).

[anders-kiaer]

Moved to #110 for better overview. Closing this.