Fix Javadoc

It was wrong. Wrong. Wrong!

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add another debug helper

Sometimes, you want to do more than just run a plugin; indeed, you
might want to run something that is not only calling a plugin but
then also verify the result, e.g. when running unit tests.

Requested by Curtis Rueden and Aparna Pal.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Test the new debug helper

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>