Assigning connector "glue" points

[Thrutchy]

Currently connectors go between the centers of 2 objects and are clipped by
the bounding boxes of the 2 objects. Without more control, the usefulness
of connectors is limited.

Something like the "glue" points of openoffice draw would be more useful.
Maybe you could even specify whether to clip at the bounding box (or better
yet the smallest bounding shape) so that the current behavior would just
correspond to a default glue point at an object center.

When an svg is to be used as a stencil (imported into another svg), you'll
also need a way to specify hierarchical glue points that will be visible to
the whatever is using the stencil. It is probably more important to
support hierarchical glue points than ones you create on-the-fly. This
hierarchical concept could also apply to object grouping. When
manipulating a group you wouldn't see glue points on objects within a
group, but you would see glue points for the group as a whole.

You could also consider using glue points outside of just connectors. Glue
points of two objects might be attracted together so that you can easily
glue 2 obects together at the glue points. A connector could just be a
path that has glue points on its endpoints. As a matter of fact, you could
make the restriction that all glue points coincide with path (end) points.
This way, stickyness would just be a property on a path point. It would
also have a nice side effect of easily ensuring glue points are on the
boundary of an object.

Glue points would obviously be useful with diagramming, but could be useful
elsewhere.