pre-merge testing on I/O branch

[Allison Randal]

As of r33639, all core tests are passing in the pdd22io_part2 branch on 
the platforms I have access to (Intel Mac 10.5.5, Ubuntu 8.04 32-bit). 
This branch takes the new I/O system that was merged into trunk a few 
weeks ago, and makes it the default, replacing the old I/O system.

I would appreciate any platform or language testing, and will merge in 
the branch tomorrow if I hear no reports, hear all positive reports, or 
manage to fix any reported problems. I see some failures in Rakudo's 
'make spectest', will check to see if they're related.

A few notes for language developers:

- Anywhere your PIR code manually created a 'ParrotIO' object, it will 
now need to create a 'FileHandle' object instead. If you used the 'open' 
opcode, then no change will be needed.

- Anwhere your PIR code called a 'slurp' method on the filehandle, it 
will need to call a 'readall' method instead.

- In C code, if you were calling a 'PIO_*' function, the name has 
changed to 'Parrot_io_*'.

Allison