Updater: complete the Fiji Wiki account hint

When registering a new update site, we have a convenient way to register
a new Fiji Wiki account at the same time -- if one is not yet available
to the current user.

However, the helpful hint was cut off, or rather, never completed by
this developer.

Pointed out by Ulrik Günther.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
ij-legacy: work around limitations of the DummyLegacyService

We should not interact with the LegacyImageMap as long as the
DummyLegacyService is active.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
ij-legacy: work around limitations of the DummyLegacyService

Even in the ImagePlus patches, we should not interact with the
LegacyImageMap as long as the DummyLegacyService is active.

This change was really intended to be part of its parent commit,
but this developer forgot that this incredibly well-written
software called Eclipse sometimes (in fact, quite often now)
ignores Ctrl+S and simply does not save the current buffer.

No cookie for you, Eclipse.

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