first pass at notebooks/geoclaw/dtopotools_examples.ipynb
updated notebook for dtopotools changes.  animate_dz_colors no longer works.
improved dtopotools_examples.ipynb example to include SIFT model, new animation, improved documentation, etc.
Added a topotools_examples.ipynb notebook
cleaned up reloads
updates to topotools and dtopotools notebooks
Added Okada.ipynb notebook
removed output and fixed Okada.ipynb
modified Okada.ipynb for changes to geometry in geoclaw@8918097a534
updated dtopotools_examples.ipynb, DZ --> dZ
Change clawpack.org/geoclaw to geoclaw.org when downloading topo files
Merge pull request #38 from rjleveque/dtopotools_notebook

Merging  notebooks/geoclaw/dtopotools_examples.ipynb and also topotools_examples.ipynb and Okada.ipynb