Make images and drawings more relevant in cards?

[badlydrawnrob]

A simple card could be provided to make working with images explicit.
This could be real useful for kids, to Storify their revision cards.

• Remove the ability to add an image in the pre block?
• There's image occlusion for some use cases, but it's clunky.
• A simple image or whiteboard sketch would be handy
• Image could come up top (under the header) and have a reveal?
• Group cards together as a sort of "story" with images.
• Draw! #50 I've been meaning to do something with this for ages.

A project, for instance, could be grouped with tags (there's not really a way to link cards together)

We're already:

• Use HTML mode by default for pre block and other fields #62

I feel like adding an image can be a bit messy combined with the pre block — an image can be a useful aid but might be worthwhile splitting out into a Draw! #50 note type, which could use image occlusion (although that kind of note forces you to add a box to cover parts of the image, or it won't let you save the note).

I'm keeping it as pre block | image field type for now, as Anki's fields are quite flexible allowing for a markdown block, an image, or both together.

I might decide to change the docs to only pre block to simplify later.