Add imagej.deleteOtherVersions property

[stelfrich]

Add a property to define overwriting behavior in more fine-grained manner (when compared to delete.other.versions):

• imagej.deleteOtherVersions=never: do not overwrite files in destination
• imagej.deleteOtherVersions=always: do always overwrite existing files in destination
• imagej.deleteOtherVersions=older: overwrite older versions (i.e. keep newer ones)

This deprecates the old delete.other.versions and will show a warning whenever it is explicitly set. If it is not set, the expected behavior is kept.

[stelfrich]

Taking inspiration from #10, we could include imagej.deleteOtherVersions=incompatible to delete other versions if it is incompatible according to SemVer, i.e. a different major version.

[stelfrich]

we could include imagej.deleteOtherVersions=incompatible to delete

After a short discussion with @ctrueden, we have decided to not implement that as a separate option but give a warning if imagej.deleteOtherVersions=older and you are overwriting with an incompatible version.

[stelfrich]

Thanks to a lot of help from @ctrueden (seriously: thanks for https://github.com/scijava/scijava-common/commit/82ce585ca0a676d12ee1f612664766cb1ac1cd4d!) this is good to merge once scijava-common:2.66.0 is released.

[ehrenfeu]

This should also be reflected in the corresponding section of the Developing ImageJ in Eclipse page, right? If you agree, I can simply update the wiki...

[stelfrich]

Good catch @ehrenfeu. Feel free to update the wiki - I would appreciate it :+1:

[ehrenfeu]

Done :heavy_check_mark: