Copied from http://xproc.org/library/recursive-directory-list.xpl

Copyright situation unclear.

Changed the namespace prefix from l to tr (and the namespaces accordingly).

Prepended a cxf:info step because the step would fail sometimes with Calabash 1.1.4 even if there was a try/catch around it.

In addition, in order to deal with a similar error, replaced p:value-available() with default values (empty strings) for include-filter and exclude-filter.