[GCAD] Added Graph, DirectedGraph and UndirectedGraph.
[GCAD] Added NavigationGraph, NavigationGraphNode and NavigationGraphEdge.
[GCAD] Added NavigationGraphNodeEntity, NavigationGraphEdgeRenderComponent, NavigationGraphEntityList and NavigationGraphRenderer.
[GCAD] Added NavigationGraphEdgeGenerator.
[GCAD] Removed IRenderNode and IRenderNodeHost.
[GCAD] Added IRenderComponent and IRenderModifierComponent.
[GCAD] Added NullRenderComponent and NullRenderModifierComponent.
[GCAD] Implemented SceneGraph, SceneGraphNode and derivatives, but not bounding volume management.
[GCAD] Added SpatialNode2d and SpatialNode3d classes.
[GCAD] Fixed AggregateSpatialQueryable2d:TraceLine () and AggregateSpatialQueryable3d:TraceLine () not setting the LineTraceResult's line.
[GCAD] Added Meshes.CreateAxisAlignedCube () and Meshes.CreateAxisAlignedWireframeCube ().