Support for shared contexts

[scheibel]

Besides the interface to mark two (or more) contexts as shared, the registries needs to be split up to have both shared and unshared data.

Typically shared data:

• State of OpenGL Objects as
  • Program
  • Shader
  • Texture
  • Buffer
  • ...
• Loaded Files
• Named strings (?)

Typically unshared data:

• State of compound OpenGL objects as
  • Vertex Array
  • Framebuffer
• OpenGL version (?)
• Implementation strategies

[scheibel]

As said in https://www.opengl.org/registry/specs/ARB/shading_language_include.txt, named strings are part of shared objects between shared OpenGL contexts.