Latin grammar: clean up and update

This patch removes all superfluous files from the directory, especially the
binary files in the doc folder. They are still available in the git
repository http://github.com/daherb/GF-latin which is still the main
repository for the development of the latin grammar.
The GF files are updated to a state close to the one at the end of the GF
Summer School 2015 where they were extended to support the MUSTE grammar.

src/latin/ExtraLat.gf

@@ -1,4 +1,6 @@
-concrete ExtraLat of ExtraLatAbs = CatLat ** 
+concrete ExtraLat of ExtraLatAbs =
+	 CatLat,
+	 ExtraLexiconLat ** 
   open ResLat, Coordination, Prelude in {
   lin
     UsePronNonDrop p = -- Pron -> NP
@@ -6,6 +8,6 @@ concrete ExtraLat of ExtraLatAbs = CatLat **
 	g = p.g ;
 	n = p.n ;
 	p = p.p ;
-	s = p.pers ! PronNonDrop ! PronRefl ;
+	s = p.pers ! PronNonDrop ! PronNonRefl ;
       } ;
 }