Template antioch_version for basic_ostream usage

Reworks antioch_version_stdout to delegate to antioch_version.  New
antioch_version accepts any templated basic_ostream you like, avoids
repeatedly flushing the stream via std::endl, and returns the stream for
later use.

Result is, caveat build time, identical on my system.

Desirable as dumping version information to a ostringstream can be handy
at times.