Remove books/matteo.sb

This was an old test book that doesn't belong here any more.

books/matteo.sb

@@ -1,28 +0,0 @@
-{
-"template" : "data.tex",
-"lang" : "french",
-"bookoptions" : [
-    "importantdiagramonly",
-    "repeatchords",
-    "lilypond",
-    "pictures"
-  ],
-"booktype" : "chorded",
-"subtitle" : "Matteo's songs",
-"content" : [
-    "hubert-felix_thiefaine/sentiments_numeriques_revisites.sg",
-    "jean_leloup/promeneur.sg",
-    "maxime_le_forestier/parachutiste.sg",
-    "yves_simon/les_bateaux_du_metro.sg",
-    "soldat_louis/du_rhum_des_femmes.sg",
-    "soldat_louis/tirer_des_caisses.sg",
-    "soldat_louis/savannah.sg",
-    "leonard_cohen/winter_lady.sg",
-    "leonard_cohen/a_bunch_of_lonesome_heroes.sg",
-    "leonard_cohen/the_old_revolution.sg",
-    "jacques_higelin/je_ne_peux_plus_dire_je_t_aime.sg"],
-"authwords" : {
-  "sep" : ["and", "et"]
-  },
- "datadir" : ".."
-}