Refactored angle-prefab: Building Circle-Segment (used as the angle-representation) from Script now, using Mesh-API. Now angles > 90 degrees look much better (are not stretched or compressed in an ugly way), and potentially also angles > 180 degrees could be measured.

Fixed Text on Angle-GO and creating the Text on both sides. Fixed Transparency-Problem by making Text only visible from the front (by 'Pass {Cull Front...}' in TextMeshPro-Shader)