Ring visualisation now parented under RingAndCircle and can be deleted together

Updated Circle prefab visuals
Removed text from Circle prefab

Also changed rendering of Circle prefab to Cylinders

Moved setting of collider shared mesh from FactSpawner to TorusGenerator
Also adjusted position of Torus Text

added 'Ring' Layer
fixed ring Collider
added snapping to ring in WorldCursor

Added scripts for generating circle-, cone and torus shaped meshes
Added fact visualisation for CircleFact as torus
Moved CircleSegmentGenerator under MeshGenerator

+MainMenue: Create new Stage files via UI +StageStatic: differentiate between developing and playing

+Added Scenes: MainMenue, LoadingScreen +Stage: Save-Load fuctionality +Sorted Prefabs and Scripts Folder

+FactOrganizer: hid FactDict +Facts: re-renamed URI to Id, enabled persistend, generated and compact LabelNamingSpace

+Restart: reenabled RestartLevelButton +Level: reenabled Level-completion +FactOrganizer: scetch for dynamic LevelGoals, with-> +FactComparer +ShinyThings: TODO: multiple highlited facts at once

+added Lot&Pendulum-Tool +Using Math3d lib for VectorCalculus +Changed Fact managment (unstable\!) +Misc refactoring

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)

Adjusted the AngleMode from 2 Lines to 3 Points AND Adjusted the AnglePreview for it, because we now can't assume to have Lines between the points

Now really Fixed the problem. Problem was: Vector3.angle() not only returns only values < 180° but also only absolute angle-values