Add script editor templates from Fiji's Script Editor

With ImageJ2's script editor, every component can ship their own
templates simply by bundling things in the /script-editor/ directory
of the .jar file. To provide everything needed for Fiji to switch
to the new script editor, imagej-legacy needs to take custody of the
templates for use with the legacy ImageJ 1.x classes.

This commit brings a verbatim copy of the templates from Fiji's
Script Editor. In the next commits, we will work on them more.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add a TestDrive for the editor in legacy mode

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Move the ImageJ 1.x macro templates to a more appropriate folder

The directory in which the templates are stored indicates the name
of the language. The name 'Macro' is awfully general, however. So
let's stick with 'IJ1 Macro'.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add a method to IJ1Helper to evaluate macros

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add an almost JSR-223-compliant script engine for ImageJ 1.x macros

This is a crucial building block to allow Fiji to switch over to ImageJ2's
script editor: Fiji *needs* to support ImageJ 1.x macros in the script
editor, otherwise users will actually say something.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
TEMPORARY snapshot coupling for testing

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

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