Due to GObject Introspection we can't have the last part of an
identifier start with a digit, since that part will be used in Python
as the identifier, and Python doesn't allow that to start with a digit.
e.g. GIMP_ROTATE_90 would be used in Python as
image.rotate(Gimp.RotationType.90)

To fix this we add DEGREES in front of the number, without a '_',
even though that looks ugly.