Make menhir a bit more verbose by passing -lg 1 -la 1.

This helps see at a glance how the automaton is affected by a change.

Makefile.menhir

@@ -45,7 +45,7 @@ MENHIR ?= menhir
 ## Menhir compilation flags
 
 MENHIRFLAGS := --explain --ocamlc "$(CAMLC) $(COMPFLAGS)" --infer\
-	--lalr --strict --table \
+	--lalr --strict --table -lg 1 -la 1 \
         --unused-token COMMENT --unused-token DOCSTRING --unused-token EOL\
         --unused-token GREATERRBRACKET --fixed-exception