Add p5-Xapian 1.4.3.0

This module wraps most methods of most Xapian classes. The missing classes and
methods should be added in the future. It also provides a simplified, more
'perlish' interface - as demonstrated above.

The Xapian library is evolving very quickly at the time of writing, hence any
documentation placed here would be likely to become out of date quite rapidly,
and I do not have the patience to write some which could rapidly become
redundant.

WWW: https://xapian.org/