Explore potential of adding open/close to IFstream, OFstream

Arose from an email from @landmann where someone was wishing to close a file and free resources, but without using the workaround of an autoPtr.

• looks fairly reasonable to do.

mentioned in issue #532 (closed)

If we are willing to restrict ourselves to not changing the compression types after the initial open, this is realizable without changing the underlying ISstream and OSstream to use pointers instead of references. (see commit 730f0f8d)

closed