[Libguestfs] [PATCH libguestfs 0/3] options: Describe --key SELECTOR in a single file.

The libguestfs part of this change. Also a virt-v2v part will be needed. The first patch adds a new feature to podwrapper so that we can use __INCLUDE:file__ directives within the POD itself (instead of using --insert, and one day replacing that). The second patch shows how this change could be used for the included parts of the guestfish man page, including the non-English pages under po-docs/$language. The third patch unifies the --key SELECTOR documentation using this mechanism. Note this also unifies the translated documentation too, although because of the way it works no actual changes are needed to po-docs/ Rich.