Use array refs instead of arrays in get_part.  This should speed things up somewhat due to less shoveling around of values.

Signed-off-by: Shawn Laffan <shawnlaffan@gmail.com>
Always set the first point in contains_point so we don't need the defined check anymore.

Signed-off-by: Shawn Laffan <shawnlaffan@gmail.com>
Add get_* methods for coords.  These will give speed improvements in the heavier usage areas.
Need to add POD details for them.
Updates #10

Also add more commentary in the contains_point sub.

Signed-off-by: Shawn Laffan <shawnlaffan@gmail.com>