Initial import of xsh-1.8.2 from pkgsrc-wip, packaged by pancake with

Initial import of xsh-1.8.2 from pkgsrc-wip, packaged by pancake with
minor changes by me.

XSH is a fast and powerful command-line XML editor. It may be used to
query and modify XML documents. XSH may be used either interactivelly or
for off-line processing (like bash). XPath expressions are used to
select parts of XML document to be processed.

Both system shell and perl are accessible from XSH in a very natural
way. XSH itself is written in Perl and uses XML::LibXML bindings of
gnome-xml2 library in the background level.