Add a link_activated event to Label
wip commit
allow snapping to like edges

this allows snapping e.g. a left edge to a left edge, as opposed to an
opposite edge.
update resize detection

this updates the dock frame to only inform the dock manager of a resize
if the frame has actually changed size.
Make graph traversal more efficient

This update the proximity graph to use a tag marker for indicated
visited nodes, instead of heap allocating a set.
Update Z-order handling for linked frame groups

If a frame is raised which has a linked frames, the other frames in the
group are raised as well, maintaining their relative Z-order.
handle the toplevel change of a dock container

This properly adds/removes a dock container from the proximity handler
when the toplevel state of the container changes.
remove unused method
Merge pull request #26 from nucleic/snap-fixes

Snap fixes
Cut the 0.7.13 release
Allow the docking rubber band to be styled.
remove unused button images
ws commit
add a live drag attribute to the DockArea
doc commit
implement control for opaque item resize
update dock band border colors
make PopupView bg transparency configurable
simplify the layout for QDockArea

This also provides the layout seed for supporting dock area tool bars.
cut the 0.7.14 release