1.5.0

With this release we switch to using WebGL 2.0 canvases if available. This enables volumetric rendering and will allow us to implement other sophisticated rendering techniques in the future.

Preliminary volumetric rendering is implemented with support for orthorhombic boxes only (e.g. file formats that do not use a matrix transformation, so unfortunately ccp4 isn't supported yet).

APIs for shared sessions, which enables an "active learning" environment for education are provided.

Clickability for cartoon traces, python integration fixes, improved documentation, better handling of changing device pixel ratios, default to higher resolution rendering, additional tests and bug fixes.