Fix runPlugIn("ij.IJ.init")

When moving this from the previous spot (where it intercepted a different
method), we forgot to adjust the parameter index.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Ensure that runPlugIn("ij.IJ.init") works.

Like, forever.

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