Support workflow for correctly matching the data with a Cesium context

[priscavdsluis]

The workflow consists of the following:

1. The user picks a WGS84 x,y, z coordinate (on Google maps for example). The point is the zone of interest.
2. Internally these points are converted to the coordinate system of the original model (e.g. Amersfoort / RD New + NAP height)
3. All the xyz-coordinates are shifted (subtracted) with the x-value, y-value and z-value of the point from step 2.

Config example:

	"shift_coordinates": {			--- optional
		"crs_transformation": {      --- optional
			"source_epsg": 7415,
			"target_epsg": 4979
		},
		"shift_x": 51.3,		
		"shift_y": 3.4,
		"shift_z": 40
	},

[priscavdsluis]

Make sure that compound CRS can be used, for example EPSG 32617 (WGS 84 / UTM zone 17N) + EPSG 5703 (NAVD88 height)

Edit: this will be done under #83