Remove unused import

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Updater (upload-complete-site): handle platform-specific files carefully

We do not necessarily want to remove files from the update site we are
uploading to when said files are specific to platforms other than the
one we are uploading from (and hence not installed locally).

Let's skip removing all files we do not expect to have because of a
different platform.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Updater: Add an API to specify the updateable platforms

In scenarios such as keeping an update site for Micro-Manager
up-to-date, it is often not only convenient, but even required to be
able to set the list of platforms for which to upload/download. This
commit adds that functionality.

As a special convenience, specifying "all" as a platform adds all the
platforms the updater knows about.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Updater (cmd-line): add --platforms to 'upload-complete-site'

This change exposes the freshly-added API to the command-line updater.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add a unit test for platform-specific upload-complete-site

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Merge branch 'upload-complete-sites'

This branch intends to support Micro-Manager's workflow better.

Micro-Manager is special in the ImageJ ecosystem because it contains
platform-specific components, so-called device drivers and device driver
adapters.

The Micro-Manager team already maintains nightly builds for Windows and
MacOSX, and we want to enable them to add a simple call to the
command-line updater to upload the changed files to their update site.

However, the builds are platform-specific, therefore we have to be
careful not to remove, say, MacOSX-specific files when uploading, say,
from the Windows 32-bit build (which simply does not produce the
MacOSX-specific files). The major change introduced by the
just-merged topic branch is to tell the updater that it is okay if there
are missing files for platforms other than the one we are currently
uploading for.

The only remaining obstacle now is to nudge the Micro-Manager team to
move the platform-specific files into the corresponding subdirectories
of lib/ so that the different platforms can be updated from the very
same site (at the moment, all the device drivers are located in
Micro-Manager's root directory, making it impossible to drive even
32-bit and 64-bit Windows versions from the same Micro-Manager
installation).

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