Add aliases for all types for their X11 protocol names

[Antikyth]

A lot of types have been renamed in XRB for clarity, but people who are familiar with the existing names may find them hard to find. #[doc(alias = ...)] attributes can be added with the names people are familiar with.

For example (pseudocode)

// ... x11::event ...

derive_xrb! {
    #[doc(alias = "FocusOut")]
    pub struct Unfocus: Event(...) {
        ...
    }
}