fn tests: prop2po simple file conversion
fn tests: prop2po processing directories
optrecurse: order the format types string

Otherwise its hard to test the list as the order always changes.
argparse: ensure argparse for 2.6

argoarse is included in 2.7, so we only need this for 2.6.  On 2.7 the
system should already be supplying this, on 2.6 it will most likely be
installed or upgraded.