remaining dataenc to sandi conversions

I've tested all the dataenc to sandi conversions except Assistant.XMPP,
and all have unchanged behavior, including behavior on large unicode code
points.

debian/changelog

@@ -40,6 +40,8 @@ git-annex (5.20150421) UNRELEASED; urgency=medium
     honoring the setting of HOME. Instead, copy msysgit's ssh into PATH.
   * Windows: Roll back to an older version of rsync from cygwin.
     The newer version has some dependency on a newer ssh from cygwin.
+  * Switch from the obsolete dataenc library for base64 encoding to sandi.
+    (Thanks, Magnus Therning)
 
  -- Joey Hess <id@joeyh.name>  Tue, 21 Apr 2015 15:54:10 -0400
 

debian/control

@@ -11,7 +11,7 @@ Build-Depends:
 	libghc-hslogger-dev,
 	libghc-pcre-light-dev,
 	libghc-cryptohash-dev (>= 0.11.0),
-	libghc-dataenc-dev,
+	libghc-sandi-dev,
 	libghc-utf8-string-dev,
 	libghc-aws-dev (>= 0.9.2-2~),
 	libghc-conduit-dev,