JHotdrawImageCanvas: make disposable

The fix to cause the JHotDrawImageCanvas to clear itself (via its
removeAll method) was incorrect and did not actually free its resources.

To remedy this, it now implements Disposable itself. The
SwingImageDisplayViewer#dispose now chains to
JHotDrawImageCanvas#dispose, which appropriately clears its list of
figureViews.
Update to pom-scijava 1.133

This updates to SCIFIO-0.9.2, which includes a critical bug fix to avoid
busy polling loops keeping the JVM alive.