Pty Library

[Cameron Taylor]

I've made the same sort of changes to the PTY driver as Andrew suggested for
the pipe driver.

1. Corrected copyright statements.
2. Dropped references to "Library" everywhere, including changing from
"ptylib_" to "pty_"
3. Updated to match new pipe interface, including removing the timeouts.

The ecos.db entry becomes:

packet CYGPKG_IO_PTY {
    alias        { "PTY Driver" }
    directory    io/pty
    script       pty.cdl
    description  "This package contains a basic pseudo-terminal driver."
}

Cameron