ES 3.0 includes ES 2.0 verbatim. We can significantly reduce
duplication by using the same <replace> node for both APIs. Note that
the enumerations must remain separate, as ES 2.0 and 3.0 support
different tokens.
The <overload> element simplifies the addition of overloads for
backwards compatibility. It is defined similar to the <replace>
element, but instead of replacing the parameters of a function
in-place, it adds a new overload and modifies the overload instead.
Added strongly-typed enums for sections: Vertices, Shaders and
Programs. Added a number of missing enums for ES 2.0. Normalized
several APIs between OpenGL and OpenGL ES.
