new spec for IO::Path

IO::Path proposal

=head2 IO::Path

    class IO::Path is Cool does IO::FileTest { }

Holds a path of a file or directory. The path is generally divided
into three parts, the I<volume>, I<directory> and I<base name>.

On Windows, the volume is a drive letter like C<C:>, or a UNC network volume
like C<\\share\>. On UNIX-based systems, the volume part is empty.

The base name is name of the file or directory that the IO::Path object
represents, and the directory is the part of the path leading up to the base
name.

    path            volume    directory  base name
    /usr/bin/gvim             /usr/bin   gvim   
    /usr/bin/                 /usr       bin
    C:\temp\f.txt   C:        temp       f.txt

=over 4

=item Str

Stringification returns the path (volume, directory and base name joined
together) as a string.

=item volume

Returns the volume part of the path

=item directory

Returns the directory part of the path

=item basename

Returns the base name part of the path

=item path

Returns the entire IO::Path object (a no-op).

=item is-relative

Returns True if the path is a relative path (like C<foo/bar>), False
otherwise.

=item is-absolute

Returns True if the path is an absolute path (like C</usr/bin>), False
otherwise.

=item absolute

    method absolute ( Str $base = $*CWD )

Transforms the path into an absolute form, and returns the result as a new
IO::Path.  If C<$base> is supplied, transforms it relative to that base
directory; otherwise the current working directory is used.  Paths that are
already absolute are returned unchanged.

=item relative

    method relative ( Str $base = $*CWD )

Transforms the path into an relative form, and returns the result as a new
IO::Path.  If C<$base> is supplied, transforms it relative to that base
directory; otherwise the current working directory is used.  Paths that are
already relative are returned unchanged.

=back