Merge pull request #90 from rjleveque/topotools_fix_xyz

Fixed some errors in new topotools.py
Some fixes to topotools.py, adjusted plotting so pcolor and imshow pixels are centered on x,y of topo, added test data and plotting of Kahului Harbor
Merge branch 'master' into topotools_fix_xyz

Some additional fixes added to topotools beyond PR#90 that was just merged.

* master: