Stdio.write: Only report sudden closes when debugging.
Stdio.File: Stabilise the fd-properties interface.
Stdio.Fd: Converted peek() into a PIKEFUN.
Stdio.Fd: Convert read() into a PIKEFUN.
Stdio.Fd: This is now a PIKECLASS.
Documentation [_Stdio]: Added some doc.
Documentation [Stdio]: Document low-level classes.