--merge doesn't merge loaders?
Hey,

I'm using GL in a way that's largely agnostic between GL core and GLES, so I'm naturally using the `--merge` option. One thing that surprised me is that, despite GL and GLES functions sharing the same function table now, `gladLoaderLoadGLContext` and `gladLoaderLoadGLES2Context` are still considered separate functions.

Right now, it seems I have to choose the right function to call based on inspecting `GL_VERSION` myself - which seems highly redundant with what glad is already doing.

Wouldn't it make much more sense for `--merge` to create a merged loader that loads the right API function set (GL or GLES2) depending on the `GL_VERSION` string automatically?