Use dimensions, instead of min/max corners, for BoxGraphics

In order to be more consistent with other Entity geometries, such as cylinder and ellipsoid, this changes BoxGraphics to use `position`, `orientation`, and `dimensions` properties instead of `minimumCorner` and `maximumCorner` properties.  This also allows for rotated boxes (which the previous behavior did not) and opens up the possibility for a dynamic box fast-path, if the need ever arises (similar to what we do for ellipsoid).

Since `BoxGraphics` is shipping with 1.5, this is a non-breaking change and needs to go in before Monday.