Support for uploading images in question editor

[lukas-shawford]

Currently, images within questions (or in the supplemental info field) have to be uploaded externally and linked using a URL. It would be more convenient to be able to upload an image directly by browsing, or by pasting from the clipboard. There are various plugins available to do this in CKEditor:

• Image: http://ckeditor.com/addon/image
• SimpleUploads: http://ckeditor.com/addon/simpleuploads
• CKFinder: http://cksource.com/ckfinder
• (probably many others as well)

Ideally, in addition to basic support for image uploads, this should support pasting an image from the clipboard, or by dragging & dropping (like in GitHub's issue editor). It would also be really cool (though probably impossible due to security limitations) to have a button for inserting a screen clipping (like in Word); failing that, it should at least be possible to easily crop an image after inserting it.

As part of this, we would need to think about setting individual file size limitations, as well as total storage quotas per user (for all images, and other data).