Make HeadlessGenericDialog more robust

We already have a unit test that makes sure that we override all methods
in the HeadlessGenericDialog, in particular those that might have been
added to the GenericDialog class in new ImageJ 1.x versions.

However, this test can only catch things after the fact, after a new
ImageJ version was released (and picked up in Mavenized form by
ImageJA).

Let's be more proactive and add code that inserts dummy methods in the
HeadlessGenericDialog for every unhandled method. This might need to be
switched off for the unit test in question, but it should make the
headless mode a lot more robust.

This fixes https://github.com/imagej/ij1-patcher/issues/13.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add a unit test to make sure HeadlessGenericDialog is robust

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Format HeadlessCompletenessTest's source code

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Merge branch 'headless-dialog'

This topic branch intends to make the headless mode more future-proof
by trying to handle any methods that might be introduced into ImageJ
1.x' GenericDialog class in a proactive way (basically switching them
to do nothing, which might be wrong, but is better than what would be
done right now: throw exceptions).

This fixes https://github.com/imagej/ij1-patcher/issues/13.

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