QDoc needs to be able to document exposed JS functions

The QtDeclarative module exposes some JS functions through the global object for use within QML. QDoc currently does not document these at all. What would be needed is someway for QDoc to generate formatted and aggregated docs for the JS functions exported by a module to the JS global object, where the documentation of the JS functions is next to the C++ functions that they are bound to.

As modules other than QtDeclarative may expose their own JS objects and functions into QML in the future, it would be preferable that the solution not be specific to the Declarative module.