A simple STL viewer integrated with WordPress media upload system.
Upload a STL using WordPress media system, hit Insert into post and you'll
get a nice [thing] shortcode, which will produce a nice object viewer.
The [thing] tag supports several parameters:
width: the width of the viewer in pixels (default 500px)height: the height of the viewer in pixels (default 360px)class: classes to apply to the viewer container (default '')color: color of the rendered object (default #86E4FF)background: background color for the viewer (default inherit)border: border around the viewer container (default none)gridsize: size of the base plane, in object units (default 200)gridunit: distance between plane lines, in object units (default 10)