Add a StatusService and LogService targeting ImageJ 1.x

... which we will use in the upcoming sample image uploader.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Use ImageJ2's sample uploader in Help>Upload Sample Image

With the recent meltdown of the server that used to serve fiji.sc,
we needed to change a couple of things, including the sample image
uploading: the new fiji.sc server is behind a firewall and cannot be
accessed via SSH.

Happily, we did a lot of work there already and implemented a
WebDAV-based uploader in ImageJ2. Now all we need to do is to use
that uploader in Fiji, which is what this commit does.

Requested by Jean-Yves Tinevez.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Alt listener: clean up some

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Alt listener: only open menu when the ImageJ window is in focus

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add a helper to invoke tasks much, much later

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Alt listener: work around Xpra releasing Alt before switching focus

Xpra unfortunately behaves differently than X.org when it comes
to switching windows via Alt+Tab: it first releases the Alt key
and then nothing happens for a couple of milliseconds. However, we
really do not want to show the menu when switching between windows
(also because the opened menu then blocks input from the window we
switched to). Therefore, use the freshly-added class to invoke the
code much, much later and hope that Xpra switched focus by then.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Before trying to open the menu on Alt, wait 50ms

It seems that queuing the Alt key handling several times on the event
dispatching thread is not enough to give Xpra enough time to switch
windows. So let's wait a couple of milliseconds before doing that.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Merge branch 'sample-uploader'

This gets rid of Fiji's own sample uploader (which no longer works since
the death of pacific) and uses ImageJ2's sample image loader instead.

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