OpenTK.Windowing.GraphicsLibraryFramework 5.0.0-pre.8

Merged 5.0 with 4.7.5, this means that all changes made between 4.6.5 to 4.7.5 are also in this release. Functions with bool parameters and return values are now correctly bound. Enum groups now document a few functions where they are used. The singular overload of GenQuries is now correctly named GenQuery. Deduplicated internal function pointers to reduce the final binary size. Fixes a few functions like glTexImage3D that took an int parameter when it should have taken an enum instead.