Make AbstractSceneParser private

Change-Id: I79618c1f1c928dd19b6fd99b77bc5243941d3683
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>
Mark assimp parser and helpers as private

Change-Id: If22a66125735b0c378a38c3d85069dfb4e98a581
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>
The gltf parser is now private

Change-Id: If6ff04047cb3befe532a0b83f09c8c6ca1c08a35
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>
Rename MeshData -> QMeshData

Change-Id: I23a466ebd29666bed1c56f29c6f049544a4eca23
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>
Mark ObjLoader as private

Change-Id: I04f0be3d791651ac27906b7eb29c0c3a1bae831b
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>