feat: Update a PageView with where the user goes next, if the transfer is internal.

* Show this data as "Exit to" on the site.
* Change "Comes from" to "Enter from" on the site.
feat(test): Add tests for internal-transfer-from and internal-transfer-to.
feat(server): Add an `exit` reduce function.
feat(server): Add a `bounce` filter.

* refactor(server): Simplify the `entrance` filter - use an object for storage instead of an EasierObject.
feat(server): Add bounce rate to GET-site-hostname-path
feat(server): Add exit rate to GET-site-hostname-path
refactor(db): Use a streaming get in the `get` function to conserve heap.
refactor(server): Use .getStream instead of .get in GET-site-hostname-demographics.
refactor(server): Simplify route descriptions.

* Add `pipe` to a model, which pushes results to a stream.
* Do generic route handling in routes.js, for routes that follow convention.
* Add `dbQuery` to a request object before the call to the route handler.
* Simplify route descriptions - declare a template and js-resources.
* If a route handler returns a promise, generic template and error handling will kick in.
Merge branch 'exit-to-page'