Update Irene example
Update to 5.2 for sandy

Sandy is no longer working due to topography issues
Update katrina example to 5.2
Update Ike example for 5.2
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
Update dtopotools notebook to work with newer geometry functionality
Change sratch directory paths
Merge remote-tracking branch 'rjl/dtopotools_notebook' into dtopotools_notebook

Conflicts:
	notebooks/geoclaw/dtopotools_examples.ipynb
	notebooks/geoclaw/topotools_examples.ipynb
Added Okada.ipynb notebook
Accomodate dZ rename
removed output and fixed Okada.ipynb
Preliminary unstructured grid example
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