MapPosition constructor
MapPosition(])
Implementation
MapPosition(this._latitude, this._longitude, this.zoomlevel, [this.indoorLevel = 0, this._rotation = 0])
: scale = 1,
focalPoint = null,
_rotationRadian = Projection.degToRadian(_rotation),
assert(zoomlevel >= 0),
_projection = PixelProjection(zoomlevel);