[engine] Remove unused LineMeshComponent.

Author: dlyr

src/Engine/Scene/GeometryComponent.hpp

@@ -102,7 +102,6 @@ class SurfaceMeshComponent : public GeometryComponent
 
 using TriangleMeshComponent        = SurfaceMeshComponent<Ra::Core::Geometry::MultiIndexedGeometry>;
 using GeometryDisplayableComponent = SurfaceMeshComponent<Ra::Core::Geometry::MultiIndexedGeometry>;
-using LineMeshComponent            = SurfaceMeshComponent<Ra::Core::Geometry::LineMesh>;
 using QuadMeshComponent            = SurfaceMeshComponent<Ra::Core::Geometry::MultiIndexedGeometry>;
 using PolyMeshComponent            = SurfaceMeshComponent<Ra::Core::Geometry::MultiIndexedGeometry>;