py/bind: collect go values/types documentations

given a `go` package like so:

``` go
// package p does a bunch of cool things
package p

// Foo type enables people with foo things
type Foo struct { ... }

// Get returns an int of upmost importance
func Get() int { return 42 }
```

it should be possible to generate a `python` module with the correct documentation (for the module, the functions and types)
