Created PlaneConverter service

Moved all PlaneConverters to their own package and implemented a
PlaneConverterService.

This provides a single entry point for any PlaneConverter
implementations.
Updated IO utility class

Corrected signatures to match the current ImgSaver and ImgOpener
signatures.

Updated javadoc.
Converted ImgIOUtils to service

The static utility classes in io.scif.img are now services. Added an
AbstractImgIOComponent to provide an accessor for these services and
ensure both ImgSaver and ImgOpener are created with the necessary
services.