utils/python_server.sh uses the right module for each python version

Editor: Integrate tern-threejs in script editor

Simplify example as per suggestions from @westlangley and @mrdoob

Proposed example that illustrates a way to convert geometry to buffer geometry

Fixed whitespaces and removed comma

Improvements to documentation

Dev

Add Multiple Elements example

Changed transparency to opacity

The OBJ to JSON converter uses now opacity instead of transparency
attribute.

Fixes #6645

shows a solution to trying to draw lots of different HTML elements
each with a different scene

Added GL call to disable attributes when reset is called. This fixes …

Protect against invalid pixel ratio

Added GL call to disable attributes when reset is called. This fixes an issue where attribs are still enabled from previous frame but enabledAttributes structure has them marked as disabled. This lead to infamous 'attempt to access out of range vertices in attribute X' messages.

We don't usually do this kind of checks, but the renderer's pixel ratio is usually taken directly from `window.devicePixelRatio`, which is undefined in older browsers.

Unbreaks examples in IE 10 (#6628).

I didn't patch `WebglRenderer`. All browsers that support `webgl` appear to define `window.devicePixelRatio`.

Removed Raycaster.precision