Surface mesh fixes and decals
- ENH: ability to add more vertices to surface mesh as well as triangles. Recalculated UV seams when triangles are added
- ENH: added decals to Vulkan renderer
- ENH: abstracted interactor so that Vulkan interactor behaves the same as the VTK interactor with custom events.
- FIX: fixed transformations for Vulkan renderer
- FIX: fixed issue with PointSet returning incorrect number of vertices
- FIX: fixed Fresnel calculation issue (#168 (closed))