copy/move --from-anywhere --to remote

Implementation was simple because it's equivilant to
--from=foo --to remote for each other remote, followed by
--to remote when there's a local copy.

(Or, in the edge case of --from-anywhere --to=here,
it's the same as --to=here.)

Note that, when the local repo does not have a copy,
fromToPerform gets it from a remote, sends it to the destination,
and drops the local copy. Another call to that for a second remote
will notice that the dest now has a copy, and simply drop from the
second remote, avoiding a second transfer.

Also note that, when numcopies doesn't allow dropping it from
everywhere, it will drop it from the cheapest remotes first
(maybe not ideal) up to more expensive remotes, and finally from the local
repo. So the local repo will generally end up holding a copy. Maybe not
ideal in all cases either, but it seems no worse to do that than to end up
with a copy undropped from a remote.

And I'm not entirely happy with the output, eg:

	copy bigfile (from r3...) ok
	copy bigfile ok

That makes sense if you think of the second line as being
the same as what is output by `git-annex copy bigfile --to bar`,
but it's less clear in this context. Maybe add "(from here...)"?
Also the --json output doesn't have a machine-readable field for
the "from" uuid, and maybe it should?

Sponsored-by: Dartmouth College's DANDI project

CmdLine/GitAnnex/Options.hs

@@ -162,40 +162,55 @@ parseToOption = strOption
 	<> completeRemotes
 	)
 
+parseFromAnywhereOption :: Parser Bool
+parseFromAnywhereOption = switch
+	( long "from-anywhere"
+	<> help "from any remote"
+	)
+
 parseRemoteOption :: Parser RemoteName
 parseRemoteOption = strOption
 	( long "remote" <> metavar paramRemote
 	<> completeRemotes
 	)
 
--- | From or to a remote, or both, or a special --to=here
+-- | --from or --to a remote, or both, or a special --to=here,
+-- or --from-anywhere --to remote.
 data FromToHereOptions 
 	= FromOrToRemote FromToOptions
 	| ToHere
 	| FromRemoteToRemote (DeferredParse Remote) (DeferredParse Remote)
+	| FromAnywhereToRemote (DeferredParse Remote)
 
 parseFromToHereOptions :: Parser (Maybe FromToHereOptions)
 parseFromToHereOptions = go
 	<$> optional parseFromOption
 	<*> optional parseToOption
+	<*> parseFromAnywhereOption
   where
-	go (Just from) (Just to) = Just $ FromRemoteToRemote
+	go _ (Just to) True = Just $ FromAnywhereToRemote
+		(mkParseRemoteOption to)
+	go (Just from) (Just to) _ = Just $ FromRemoteToRemote
 		(mkParseRemoteOption from)
 		(mkParseRemoteOption to)
-	go (Just from) Nothing = Just $ FromOrToRemote
+	go (Just from) Nothing _ = Just $ FromOrToRemote
 		(FromRemote $ mkParseRemoteOption from)
-	go Nothing (Just to) = Just $ case to of
+	go Nothing (Just to) _ = Just $ case to of
 		"here" -> ToHere
 		"." -> ToHere
 		_ -> FromOrToRemote $ ToRemote $ mkParseRemoteOption to
-	go Nothing Nothing = Nothing
+	go Nothing Nothing _ = Nothing
 
 instance DeferredParseClass FromToHereOptions where
-	finishParse (FromOrToRemote v) = FromOrToRemote <$> finishParse v
+	finishParse (FromOrToRemote v) = 
+		FromOrToRemote <$> finishParse v
 	finishParse ToHere = pure ToHere
-	finishParse (FromRemoteToRemote v1 v2) = FromRemoteToRemote
-		<$> finishParse v1
-		<*> finishParse v2
+	finishParse (FromRemoteToRemote v1 v2) = 
+		FromRemoteToRemote
+			<$> finishParse v1
+			<*> finishParse v2
+	finishParse (FromAnywhereToRemote v) = 
+		FromAnywhereToRemote <$> finishParse v
 
 -- Options for acting on keys, rather than work tree files.
 data KeyOptions