Include public projects in project listings.

Created by: jsternberg

Firstly, this fixes the group page that would 404 even when the user had public access to some of the projects in a group. This fixes issue #5553 (closed). Public projects are now included in the "All" section of the projects page. The default dashboard doesn't show public projects though since that would cause too much of an overload of information if the number of public projects is very large. We want to make it possible for them to find public projects easily, but we don't want to overload them with information in their daily workflow.

Slightly tweaked the message when a user doesn't have access to any projects on the dashboard. It now includes a link to the public section of the site so it's more obvious where to look for that information.

The search has also been improved to include public projects.