Notes on OpenRaster support in Drawpile

As of version 0.7, Drawpile defaults to OpenRaster format for images containing
annotations or more than one layer. (The default for simple images being PNG)

The standard is still at a draft stage and subject to change, and so is
Drawpile's implementation of it.

Presently, a Drawpile specific extension is used for saving the annotations.
They are saved under the <drawpile:annotations> element.
Once the <text> element of OpenRaster is standardised, it will probably be used instead.

Compatability has been tested with the following programs:
 * MyPaint
 * GIMP
 * Krita

Further reading
 * http://www.freedesktop.org/wiki/Specifications/OpenRaster/

