updated release notes and changes for 5.2.0
added documentation of new topotool modules using automodule, which requires clawpack/geoclaw@471b83ecb and is intended for the 5.2.1 release
Merge branch 'master' into release_5.2.1

* master:
  Update shallow water example name and fix gallery build instructions.
  Fix strict version number
  Add version added comment
  Add small description of change in custom BCs
added kmltools_module.rst
more dtopotools2 documentation
Merge branch 'extra_files' into release_5.2.1

* extra_files:
  Created doc/doc/extra_files directory for files that should show up in root of clawpack.github.io, and modified conf.py to add this directory in html_extra_path
changed copyright date
Merge branch 'extra_files' into release_5.2.1

* extra_files:
  change CNAME to clawpack.org and document new way to push webpages
Merge branch 'extra_files' into release_5.2.1

* extra_files:
  fixed _templates/index.html
  fixed pointer to github.io/doc
changed DZ to dZ in doc/extra_files/notebooks/dtopotools_examples.ipynb
updated ipynb files with geoclaw link
added gallery entries for storm-surge and multi-layer examples
Merge pull request #65 from rjleveque/release_5.2.1

WIP: New docs for Release 5.2.1