WIP: Add a better infrastructure for legacy hooks

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
WIP: Register the LegacyHooks

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
WIP: Do not inject the LegacyService into ImageJ 1.x anymore

It turned out that it limited us too much to load all of the classes
required by ImageJ2's LegacyService into the same class loader as
ImageJ 1.x.

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

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
WIP: Add a class loader specifically for loading a patched ImageJ 1.x

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
WIP: Add a test for calling a fresh headless ImageJ 1.x

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Remove obsolete patches for ij.macro.Functions

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
fixup! Implement legacy hooks for ImageJ2
fixup! WIP: Add a better infrastructure for legacy hooks
CodeHacker: remove obsolete code

In our endeavor to separate better between ImageJ 1.x and ImageJ2
classes, we no longer use ImageJ2 classes directly in the patched
ImageJ 1.x.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
fixup! WIP: Register the LegacyHooks
Move IJFunctions into the LegacyInjector/LegacyHooks

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
fixup! Remove obsolete patches for ij.macro.Functions
fixup! WIP: Register the LegacyHooks
fixup! Move IJFunctions into the LegacyInjector/LegacyHooks
Move ImageJFunctions into LegacyInjector/LegacyHooks

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
fixup! Implement legacy hooks for ImageJ2
fixup! WIP: Add a better infrastructure for legacy hooks
Move ImagePlusFunctions into LegacyInjector/LegacyHooks

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
fixup! Implement legacy hooks for ImageJ2