Move some ij.IJ patches over from fiji-compat

This change makes sure that ImageJ 1.x is properly initialized when
calling macros in batch mode.

It also adds the ij.log.file handling: when this property is set,
IJ.log() will log not only to the Log window but also to the file
pointed to by the property.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Fix ImageJ 1.x quitting in legacy mode

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
squash! Move some ij.IJ patches over from fiji-compat

Say something about runUserPlugIn
fixup! Move some ij.IJ patches over from fiji-compat