Draw 3D stuff better

[markstock]

Both drawing boundaries (triangles) and particles (billboards) can be better, as can upgrading the view from orthogonal to perspective. There are three tasks here.

1. Render in perspective, this means implementing an arcball-like rotation and an allowance to move the center of rotation.
2. Render boundaries as solid with basic direct and ambient lighting.
3. Instead of drawing billboards with transparency (costly with lots of overlap, and difficulty when depth culling), we may consider using instanced rendering or geometry shaders to convert each point into a screen-space fan of 7 or 9 opaque triangles. I have code for that in my lidar viewer. With the size ratio properly set, this would look much more 3D.