The Instance Actor is required for signing http GET requests but is not a "user" and should not be otherwise interacted with.
- hides instance actor profile page, returning a 404
- excludes instance actor from search results and suggestions including in Getting Started
- replaces link to user profile in user admin page with a brief message box
- replaces panel in user admin page that allows for user to be suspended or removed with a message explaining why that is a very bad idea
fixes#3119
Hugh Rundle
f011f2bce9