This code is a stripped down version of the implementation of the Cassowary constraint
solving algorithm of the Kiwi project:

	https://github.com/nucleic/kiwi

All credits go to the Nucleic Development Team !

For the QSkinny use case the following adjustments have been made:

	- implementations moved from *.h to *.cpp files

	- replacing AssocVector from the Loki Library by yet another stupid
      implementation of a "flat map"

I forgot what version of Kiwi had been used - a migration of the code
for a more recent official version will happen soon.