draw:escape-direction is specified as *one* of auto, left, right, up, down,
horizontal or vertical but in edit points it is possible to select e.g. up and
right escape directions, save and reload and those settings are lost seeing as
they don't fit into the file format

e.g. see this attached sample, it was created with escapes of left + up + right
+ down, but this has been lost on save and on reload it will be "auto" which is
a different thing, e.g. see the preview in right->click->connector, and the
different routing used if the box is moved slightly to force a recalculation.
Re-editing the glue points to set left+up+right+down before moving does the
right thing, but is lost again on save