Restore TypeChangers ability to combine channels
Break out some code into methods
Update TODOs
Improve type changing/casting code

Now there are underlying primitive calls that avoid BigDecimals. One tests
data to determine what is the best method for casting. TypeChanger uses such
an approach to quickly and accurately cast. It can fall back to BigDecimal
based casting if needed.
Dataset updates run off EDT

Updated DefaultImageDisplay and DefaultDatasetView to call update()
methods off the EDT, as these classes are typically invoked on the EDT
and thus deadlock if a data update involves dispatching status updates.

To accommodate this, the SwingDisplayPanel now also checks for a null
projector before redrawing. This would indicate the computation has not
completed yet (and another event will be dispatched to trigger an
appropriate redraw at that time).
Remove accidental debug code
Fix minor logic error
Merge branch 'master' into fix-type-changer
Bump to pom-scijava 1.59

Signed-off-by: Jenkins <jenkins@dev.loci.wisc.edu>
Merge branch 'fix-type-changer'
Make GeneralCast the center of casting logic
GeneralCast now supports two cast() methods