Even though I haven't seen working samples with this extension,
according to some references, this is a common extension for compressed
JPEG 2000 code stream. Also our old plug-in was listing this extension,
so let's do so now as well.

To this day, the only 2 extensions we used to list in the JasPer-based
plug-in and not in the OpenJPEG one are .jpf and .jpx (JPEG 2000 Part-2)
since OpenJPEG does not have support yet. But actually I think the old
plug-in may have simply been "lying" since JasPer website says the
library is meant to implement JPEG-2000 Part-1 standard.
So I believe we are now on par (and even better on many aspects) with
the former plug-in implementation based on libjasper.