Make support of naming for other partition table types possible (#746214)

Previously partition naming had only been implemented for gpt.  Make the
code ready to support naming of the other partition table types for
which libparted supports naming.  Specifically: amiga, dvh, mac and
pc98 in addition to gpt.  Document issues found with some of these
partition table types, which can relatively easily been worked around.

Leave support of naming for partition table types other than gpt
disabled, mostly just to reduce ongoing testing effort, at least until
there is any user demand for it.

Bug 746214 - Partition naming enhancements