prawnpdf/prawn — pull request #636 by packetmonkey (2014-01-15 17:05:23+00:00)
Title: Allow a user to unregister an existing image handler

This adds functionality and a spec so we can unregister an image handler.

The use case I plan for this is to unregister the default PNG handler then append a new handler that can handle PNG images faster, without having to also handle the special case JPEG images have with PDFs by using #register! to take priority over both the existing handlers.