Added mimeencoding= term to annex.largefiles expressions.

* Added mimeencoding= term to annex.largefiles expressions.
  This is probably mostly useful to match non-text files with eg
  "mimeencoding=binary"
* git-annex matchexpression: Added --mimeencoding option.

Types/Mime.hs

@@ -0,0 +1,12 @@
+{- git-annex mime types
+ -
+ - Copyright 2019 Joey Hess <id@joeyh.name>
+ -
+ - Licensed under the GNU AGPL version 3 or higher.
+ -}
+
+module Types.Mime where
+
+type MimeType = String
+
+type MimeEncoding = String