You spin me right round

For v1.1.0, we added a simple but powerful feature to the 3D demo scenes:  camera rotation.  The user may now hold the right mouse button and drag to revolve the camera about the coordinate system origin.  This allows the user to view the various vectors displayed from different angles.  This will be of significant benefit to users new to graphing in three-dimensions.  Visualizations of 3D systems on a flat board, be it a physical chalkboard or a virtual one, are always challenging to create and to interpret, especially if one has little experience with graphing in 3D.  Being able to revolve the camera will hopefully make this visualization challenge a bit easier to tackle.