For the orthographic views, a grid is rendered (only for XY at the moment)

|SOURCE|
[OrthographicViewControl]
* Removed the per-view testing clear colours
* Orthogonal views use a dark grey
* A simple 100*100 grid spaced 10 units apart per line is rendered on the XY
  plane
* For the XY view, the grid is zoomed in and out to demonstrate that the view
  works