Add an interactive test for the legacy mode

This new test lets you start up ImageJ2 in legacy mode, for interactive
playing around and testing. You can execute it with

	mvn exec:java -Dexec.mainClass=imagej.legacy.TestDrive \
		-Dexec.classpathScope=test

or in Eclipse

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Fix tyop in Javadoc

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Use ImageJ2 logo in legacy mode

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