registerurl, unregisterurl: Added --remote option

This serves two purposes. --remote=web bypasses other special remotes that
claim the url, same as addurl --raw. And, specifying some other remote
allows making sure that an url is claimed by the remote you expect,
which makes then using setpresentkey not be fragile.

Sponsored-By: the NIH-funded NICEMAN (ReproNim TR&D3) project

Command/Export.hs

@@ -59,7 +59,7 @@ data ExportOptions = ExportOptions
 optParser :: CmdParamsDesc -> Parser ExportOptions
 optParser _ = ExportOptions
 	<$> (Git.Ref <$> parsetreeish)
-	<*> (parseRemoteOption <$> parseToOption)
+	<*> (mkParseRemoteOption <$> parseToOption)
 	<*> parsetracking
   where
 	parsetreeish = argument str