testremote: New command to test uploads/downloads to a remote.

This only performs some basic tests so far; no testing of chunking or
resuming. Also, the existing encryption type of the remote is used; it
would be good later to derive an encrypted and a non-encrypted version of
the remote and test them both.

This commit was sponsored by Joseph Liu.

Utility/Metered.hs

@@ -24,6 +24,9 @@ import Data.Int
  - far, *not* an incremental amount since the last call. -}
 type MeterUpdate = (BytesProcessed -> IO ())
 
+nullMeterUpdate :: MeterUpdate
+nullMeterUpdate _ = return ()
+
 {- Total number of bytes processed so far. -}
 newtype BytesProcessed = BytesProcessed Integer
 	deriving (Eq, Ord, Show)