Safe-guard against installing keyboard listeners in headless mode

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Let's depend on imagej proper

This is needed because we want to hand off to net.imagej.Main.

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

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Use ImageJ2's Main class instead

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Remove code from MenuRefresher that ImageJ2 made obsolete

This includes, most notably, the handling of scripts and macros:
ImageJ2 already puts them into the menu, we do not have to do it
again.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Do not override ImageJ2's editor

ImageJ2's editor has a really huge advantage over Fiji's. Well, not
only one, but the biggest one is that ImageJ2's editor does not
have to construct an ImageJ2 context: it simply has it. So it starts
up really snappily.

Other advantages include: full integration into the SciJava stack,
robust development (with continuous integration and all), support
for @-annotated parameters in macros, etc

Therefore it is high time to let Fiji use ImageJ2's editor (which
was developed starting with Fiji's editor source code) at last.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Respect argLine even for integration tests

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
WIP: Adjust BarePluginsIT to net.imagej.Main

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