OpenGL-2.13.1.0: CHANGELOG.md

2.13.1.0
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* Added `extensionSupported`.
* Relaxed upper version bound for OpenGLRaw.
* Added CHANGELOG.md to distribution.

2.13.0.0
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* Added missing drawing commands using vertex arrays and some related types.
* Added missing whole framebuffer operations.
* Added getters for `stencilMaskSeparate`, `stencilFuncSeparate`, and `stencilOpSeparate`, making them full-blown `StateVar`s.
* Added `patchDefaultInnerLevel` and `patchDefaultOuterLevel` to control the default tessellation levels.
* Added `ContextLost` constructor to `ErrorCategory` type.
* Added `SeparateAttribs` and deprecated `SeperateAttribs`, fixing a spelling mistake.