This adds the ability to use multiple books for the GUI tests. This is
helpful since some tests need special configuration, and sharing the
same book can make it difficult or impossible to test different
configurations. It also makes it difficult to make changes to the
test_book since it can affect other tests.
This works by placing the books in the tests/gui/books directory. The
test runner will automatically build all the books. The gui tests can
then just access the DOC_PATH with the name of the book.
Books are now saved in a temp directory to make it easier to use the
DOC_PATH variable, instead of being tests/gui/books/book_name/book which
is a little awkward.
Following commits will restructure the existing book. This is just a
mechanical move.
This adds the ability to redirect URLs with `#` fragments. This is
useful when section headers get renamed or moved to other pages.
This works both for deleted pages and existing pages.
The implementation requires the use of JavaScript in order to manipulate
the location. (Ideally this would be handled on the server side.)
This also makes it so that deleted page redirects preserve the fragment
ID. Previously if you had a deleted page redirect, and the user went to
something like `page.html#foo`, it would redirect to `bar.html` without
the fragment. I think preserving the fragment is probably a better
behavior. If the new page doesn't have the fragment ID, then no harm is
really done. This is technically an open redirect, but I don't think
that there is too much danger with preserving a fragment ID?
