1.23.1 (unstable):

* Document:
  - Save static image data as a child text node, not an attribute.
  - Save image data (example data or static images) in base64 format,
    instead of the GDA format.
  (Murray Cumming)
* Export to po files:
  - Also export static text items, and print layouts.
  - Avoid duplicates.
    (Murray Cumming)
* Examples: Add a static image item to the Project Manager example.
  This is just so that the feature gets some testing.
  (Murray Cumming)
* Tests: Add new tests using GdkPixbufLoader to check that we can interpret
	image data as an image.
  (Murray Cumming)