IJ1Helper: Allow modern commands to override legacy ones
IJ1Helper: Allow modern commands to override legacy ones

Unless a command is marked explicitly with a 'no-legacy' Attr, it
should be allowed to override existing legacy commands.

Signed-off-by: Johannes Schindelin <53fb8db7833fca1e1746dd8592f61048d350f64c@gmx.de>

imagej/imagej-legacy,imagej/imagej-legacy,imagej/imagej-legacy,imagej/imagej-legacy