topic-branches.sh: let the environment variable REMOTE override

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
download-launchers.sh: we can use --set-icon for the Windows icon now

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
download-launchers.sh: copy ./fiji from ./fiji-<platform>

... instead from ./ImageJ-<platform> (to help correct keep icons).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
download-launchers.sh: no longer fix ij-launcher.jar

The idea is that even ij-launcher.jar should be handled by
Retrotranslator; besides, we do not ship ij-launcher.jar from the
Fiji update site and the ImageJ update site (which does ship said
.jar file) does not fix the classes anyway.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
fiji-compat: avoid instantiating a Menu in headless mode

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Merge branch 'ij-legacy' (early part)

The only good reason, really, is to force an update of the Class-Path in
fiji-compat's manifest so that sezpoz-1.9-imagej.jar is used.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Merge branch 'master' of github.com:fiji/fiji