Refactored interface to incorperate lessons learned so far trying to implemend
a whoosh based local library.
Search now has a limit and an offset to account for fact that we need to start
doing pagination of results properly. Updates now have begin, flush and close
calls. Additionally I've added clear method to allow for easily nuking the data
store.
Extension's setup method are now passed the active registry allowing them to
"steal" a list of the registry items they care about. In the case of commands
the registry is passed via args.registry.
We now only operate on local track uris, instead of a funny mix of local and
file uris. To achieve this we instead maintain a uri->path mapping to use for
the actual scanning.
- find_uris is no more
- find_files now returns file paths relative to path being searched
- find_files now only works on directories
- find_files tests have been updated to reflect changes
- local scanner has gotten a minimal update to reflect this alteration
