Release v0.088

In this release:

Added

Added next_page/prev_page attributes to list pages. These provide better access to the page data like title to make better links for users. The existing next/prev attributes only held paths, which made finding this information more difficult. Thanks @jberger! [Github #555]
Allow Link trees in navigations to support multi-level navigations. Thanks @jberger! [Github #553]

Fixed anchor-only links on the index page being rewritten to point to the wrong page. Thanks @jberger! [Github #554]
Moved some common attributes into a role to fix API differences between Document objects and Page objects. There is a lot more cleanup to be done in this regard, and we'll be doing that before pushing out v1.00.
Fixed problems running the user's editor when there are spaces in the path. Thanks @mohawk2! [Github #557]
Fixed some test failures with running the user's editor on Windows systems. Thanks @mohawk2! [Github #557]
Removed some useless editor error states that were causing spurious test failures for no good reason.