Add service to track anonymous usage statistics
Add an interface for objects with URL locations

The initial use case is for ModuleInfo. Similar to Identifiable, it is
nice to able to ask a command or script: "In which URL are you defined?"
This is a different question than the delegate class, which is
Java-specific.
Make common module types implement Locatable
Record location of tracked objects, too

We will need this later, because we really want to verify, when
compiling usage statistics, which update site (if any) the relevant file
came from. If we cannot deduce the update site, we don't care about the
object's usage, because it is not part of the "known ecosystem" of
modules etc.