Put Device and Master methods into traits.

[trissylegs]

Rationale

1. Cards have been split.

There are now three kinds of Drm devices. card, render and control nodes. A typical setup might look like this:

$ ls /dev/dri
card0
controlD64
renderD128

(From memory, not running Linux right now. Mine also has another for my discrete card)

We can split some things into control, some things into render (and leave somethings on both).

2. There are multiple ways of getting and interacting with devices that have different semantics.

If you are root, you can open the device and call DRM_SET_MASTER to get full mode-setting capabilities, or you might open it, use x11 or wayland to computicate auth_magic and convert a card to a auth'd card,
or open render directly.

Design:

pub trait Card {
    unsafe fn ioctl<T:DrmIoctl>(&self, arg: &mut T) -> io::Result<()>;

    fn version(&self) -> io::Result<Version> {
        // Done for you
    }
    // more
}

pub trait Render: Card {
    fn create_dumbbuf(&self) -> Result<DumbBuf>;
    // etc.
}

pub trait Control: Card {
    fn set_crtc(&self, 
        crtc: Id<Crtc>, 
        fb: Option<Id<Fb>>, 
        x: u32, y: u32, 
        connectors: &[Id<Connector>],
}

This does expose ioctl and DrmIoctl, but I did plan on doing that anyway.