some proposed changes

[Huw Rogers <count0 building2 co jp>]

After some hacking I made recursive types work. It was actually
surprisingly easy.

I also want to propose changes to the way structure, sequence and any
marshalling work:

* if a structure field is not defined in the Perl hash, then it is
marshalled as if an undefined scalar. Right now it dies, which requires
Perl scripters to exhaustively initialize every structure member even if
they'd prefer the ones they leave out to default to undef. It would also
be consistent with C struct usage (where unmentioned struct members in
static initializers default to zero-initialized memory) to have default
undef behaviour.

* if a sequence is undef, it is marshalled as a zero length sequence.
Right now if it is not a true reference to an array it dies.

* if an any is undef, it is marshalled as a null Any. Right now if it
is not a true reference to a 2 element array it dies.

If anyone disagrees with the above, then plz speak out. Unless there's
disagreement, I'm going to include these changes in 0.4.4.

	-Huw
-- 
Huw Rogers <rogers building2 co jp>