cal2rdf.pl > v1.13 does not like X-WR-CALNAME before PRODID

Hi all,

I have been recently playing [W3C hat off] with RDF Calendaring and 
found the ical2rdf perl script truly useful.

As I have found, apparently the version of iCal I have (1.5.1) declares
PRODID after the first X-* header (namely, X-WR-CALNAME)

sample iCal file: [[
> BEGIN:VCALENDAR
> VERSION:2.0
> X-WR-CALNAME:test
> PRODID:-//Apple Computer\, Inc//iCal 1.5//EN
...
]]

ical2rdf.pl version 1.13 and above added a mechanism relying on finding 
PRODID to generate the xproperty namespace, which is a useful 
user-friendly feature, and a good idea since PRODID is apparently 
required and thus *is* there somewhere in the iCal file... but since 
X-* properties may (and indeed, do) appear before PRODID is declared, 
it causes the script to die on (line 244):

          die "X- property ($n) requires PRODID field";

A quick scan through RFC 2445 ("4.8.8.1 Non-standard Properties") does 
not appear to make this behaviour illegal, so this appears to be a bug 
in ical2rdf.
I don't have a miracle solution figured out yet. I suppose ical2rdf.pl 
could be modified to parse the ics twice, once in search of PRODID and 
then a normal parse.

Cheers,
-- 
olivier