Add Madurese (mad) (#104)

This is needed for better support of the Wikipedia Incubator
( https://incubator.wikimedia.org/wiki/Wp/mad )
and translatewiki.

Autonym spelling according to this dictionary:
Adrian Pawitra, "Kamus lengkap bahasa madura—indonesia"
(The title is in Indonesian and hence spelled differently.)

data/langdb.yaml

@@ -353,6 +353,7 @@ languages:
   lzh: [Hant, [AS], 文言]
  # Also Geor, but the incubator is in Latn
   lzz: [Latn, [EU, ME], Lazuri]
+  mad: [Latn, [AS], madhurâ]
   mai: [Deva, [AS], मैथिली]
   map-bms: [Latn, [AS], Basa Banyumasan]
   mdf: [Cyrl, [EU], мокшень]