Restructure Render Contexts to OpenGL Contexts

Rendercontexts need to be changed to OpenGLContexts and decoupled from the OpenGL object. The UI controls will then create a context and activate it only as needed.

Start by locating the RenderContext and OpenGL objects, then trace how the UI controls create and use them. The requested restructuring should decouple OpenGLContexts from the OpenGL object and have UI controls create and activate contexts only when needed; the issue names no files or tests, so the completion criteria need clarification.

Written by the indexing model from the issue text.