Support Doc Pages For Functions

[JordanRL]

Currently the generator supports documentation for classes, traits, and interfaces, but not user defined functions.

Though I don't see a very good way to inspect and support anonymous functions or global scoped closures, actual defined functions could be supported.

[JordanRL]

I'm removing this from the 0.2 milestone.

I looked at several different ways to implement this, and there are some very opinionated choices that would need to be made. Since I don't typically use PHP for functional programming, I'll defer this until I get some feedback or requests for particular ways of exporting and organizing this type of data.