SingleInstance issues

[ngladitz]

I currently see the following with the SingleInstance listener enabled:

Scenario 1:

• Start ImageJ without file arguments; the SingleInstance listener unexpectedly does not get started / does not start listening

Scenario 2:

• Start ImageJ with file argument; the SingleInstance listener does start listening and the file given on the command line gets loaded via IJ1Helper.openImage() with the interception of DefaultLegacyHooks
• Start a second ImageJ instance with a file argument; the SingleInstance listener communicates the file argument with the first instance but the file is opened via IJ1Helper.openAndAddToRecent() without the interception of DefaultLegacyHooks

I tried replacing the call of openAndAddToRecent() with openImage() to fix the issue in the second Scenario after which interception seems to work but then images opened via SingleInstance show odd behavior like being displayed with a very tiny default scale or colors being scaled differently (compared to opening the same image via e.g. File -> Open) and for some files (in my case BioFormats OBF with local / non-upstream modifications) I get two visually very distinct display windows (including title and image content) for the same series (though I only see openBytes on the reader being called once).