rather large, but then again so are the number of geometry parameters, so
it's only fair. This should cover calculating all parameters given a signle
descriptor and given rel_to_1, rel_to_2, confine_to objects. Only calculation
of text params is left. I think that will be as simpl as a "copy them across
from the description", but I may yet decided to complicate that a bit.
SVN revision: 6973