Generate source code pages for all PyClaw examples.

Also add links to them in the gallery.
Fix paths by removing some extra '/'s.
Add pages with source code for PyClaw examples.
Fix claw_html_root to point to local images.
Merge branch 'pyclaw_gallery_sources' of https://github.com/ketch/doc into install

Testing if I can build galleries for pyclaw.

* 'pyclaw_gallery_sources' of https://github.com/ketch/doc:
  Fix claw_html_root to point to local images.
  Add pages with source code for PyClaw examples.
  Fix paths by removing some extra '/'s.
  Generate source code pages for all PyClaw examples.
added more clawpack/apps/fvmbook examples to gallery