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 dynamic navigation of headers of the current page in the
sidebar. This is intended to help the user see what is on the current
page, and to be able to more easily navigate it. The "current" header is
tracked based on the scrolling behavior of the user, and is marked with
a small circle. This includes automatic folding to help keep it from
being too unwieldy on a page with a lot of nested headers.
This includes the `output.html.sidebar-header-nav` option to disable it.
I'm sure there are tweaks, fixes, and improvements that can be made. I'd
like to get this out now, and iterate on it over time to make
improvements.
