* Remove duplicate link to Hyper integration
The `Adding a Server` page contains a duplicate link to `Hyper`. The first of them can cause the reader to accidentally skip the `Rocket` and `Iron` integration pages because their pages are before the one for `Hyper` in the reading order.
Remove the first link so that the list of official server integrations matches the page order.
* Match the list of integrations to the page order
In the book, the pages for the official integrations appear in the order: `Warp`, `Rocket`, `Iron`, `Hyper`, but on the `Official Server Integrations` page they are listed with `Hyper` first. This can cause readers to accidentally skip the other three integrations if they click on the link for `Hyper` first.
Move `Hyper` to the bottom of the list to match the reading order of the book.
* Remove unnecessary blank line
* Use mdbook for building the book
* Update book config
* Update book hierarchy to work properly with mdbook
This necessitated adding place-holder index pages
since mdbook does not suppoert stand-alon menu items
* Update tests to use 2018 edition
* Fix various compilation errors in the tests
