matplotlib Code

add Shapely as a Requirement.

use nice colors for ocean and land

add hires.py example.

update high-res dataset install instructions.

updated for new boundary files

remove debug code

fix Antarctic polygon closing code

optimize code for closing Antarctica

Further speed improvements. For collections, now has faster ignoring
of elements that aren't provided, such as offsets. Paths now do not
even store the "default" codes array -- which is MOVETO followed by N
LINETOs. These are generated automatically by the iterators if no
codes array is provided. (Should also result in significant memory
savings for graphs with many points.)

use npy.sum, not built-in sum