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Signed-off-by: Curtis Rueden <ctrueden@wisc.edu>
POM: update to pom-imagej 2.6
POM: add used-but-undeclared dependency
LegacyImageJApp: fix priority

The ImageJApp priority changed to HIGH, so LegacyImageJApp needs to be
higher than that, now.
Remove legacy ImageJ app

This code migrated to the toplevel net.imagej:imagej component:
https://github.com/imagej/imagej/commit/2300d79ef55d9fd360bfda0c38713dbc64f55c65
Temporarily bump ij1-patcher to a -SNAPSHOT version

The ij1-patcher *just* merged support for the hooks that we are about
to tap into.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add a plugin type to intercept ImageJ 1.x' opening images

This plugin type will need to be implemented by all plugins wanting
to have a say how an image is opened.

It is our design to improve on HandleExtraFileTypes; Now developers
can extend ImageJ 1.x' image opening without stepping on each others
toes, badly.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
DefaultLegacyHooks: support LegacyImageOpener plugins

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
WIP: add DefaultLegacyImageOpener
Refactor LegacyImageOpener to LegacyOpener

We want to broaden the functionality of the LegacyImageOpener. Instead
of just directly using SCIFIO to open a provided dataset, we should be
delegating through IJ2 to get the full "File>Open" experience. This
requires the potential to add hooks in the IJ.open method, which
requires a more general LegacyOpener.
Consolidate LegacyOpener to one signature

Instead of separate signatures for open and openImage, add a display
flag and consolidate to a single signature.
wip: implement DefaultLegacyOpener

Supports Images only for now
Add ij1Helper to DefaultLegacyHooks

DefaultLegacyHooks now has an ij1Helper instance for use in overriding
IJ1 commands, without the IJ1 class imports bleeding into additional
classes.

IJ1Helper requires a DefaultLegacyService explicitly, so
DefaultLegacyHooks will only get a helper when it's constructed with a
DefaultLegacyService. This is accounted for in the DefaultLegacyService,
which constructs its DefaultLegacyHooks using a freshly created
IJ1Helper.
WIP: intercept open