final changes for 5.2.1 version numbers and release notes
Merge pull request #69 from rjleveque/release_5.2.1

final changes for 5.2.1 version numbers and release notes
updated comments about new tools added in 5.2.1
added geoclaw notebooks
TODO: check description of how regions work
updated changes_to_master
updated gallery.py to include new fgmax examples and also modified so that if figure has no associated html file then the link points to the png, needed for fgmax plots created with otherfigure.
added warning to installing about pre-release version
bumped version to 5.2.2
fixed gallery.py to properly point to png when no html
Merge pull request #71 from rjleveque/for_5.2.2

For 5.2.2