Organize imports

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Safeguard against uninitialized ImageJ 1.x

There is a bug in ij1-patcher 0.4.2 that prevents ImageJ 1.x from being
initialized properly when running

	IJ.runPlugIn("ij.IJ.init", "");

Even though we have fixed this in ij1-patcher, let's safeguard against
this problem for the future.

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