Bump to pom-scijava 1.157

Signed-off-by: Jenkins <jenkins@dev.loci.wisc.edu>
Bump to pom-scijava 1.158

Signed-off-by: Jenkins <jenkins@dev.loci.wisc.edu>
Bump to pom-scijava 1.160

Signed-off-by: Jenkins <jenkins@dev.loci.wisc.edu>
Tidy up the POMs

This was done using:
    mvn tidy:pom
POM: remove unneeded dependencies

At least, I hope they are unneeded. They cause all sorts of downstream
problems with dependency:analyze. And are almost certainly unneeded
*except* for XML-processing-related tasks, which are totally unrelated
to SCIFIO core.
Clean up dependencies
IO: restore broken API

Restored the openImg API that returns a single ImgPlus. Renamed the
List-based API to "openImgs".

TODO: same treatment for ImgOpener
TODO: should have refactored the openImg names. make sure nothing is
using deprecated methods.
ImgOpener: restore deprecated API

Renamed "List openImg" methods to "openImgs". Restored the "openImg" API
which returns a single ImgPlus and marked it deprecated.

All openImg implementations are trivial delegates to the corresponding
openImgs method, with a get(0) on the result.