-fix daemon functions to start/stop lbry files
-remove unused stuff in LBRYFileManager
-improve and use new get_lbry_file function instead of _check_history,
which didn’t use the lbry file manager
-use said function to let delete_lbry_file use the same search keys
(sd_hash, name, and file_name)
-logging in LBRYDownloader
-Add LBRYFileProducer, to host the contents of a download without
having to keep re-opening it as it is added to
-included sd hash in ManagedLBRYFileDownloader, to make comparing the
contents of the file manager against name claims easier
-add get_lbry_file function, which returns information about a LBRY
file found by sd_hash, file name, or lbry uri
