organize coq sources in subdirectories

coq/_CoqProject

@@ -1,28 +1,17 @@
 -R . LadderTypes
-AdditionalTactics.v
-ListFacts.v
-FiniteSets.v
-FSetNotin.v
-Atom.v
-Metatheory.v
+metatheory/AdditionalTactics.v
+metatheory/ListFacts.v
+metatheory/FiniteSets.v
+metatheory/FSetNotin.v
+metatheory/Atom.v
+metatheory/Metatheory.v
 
-terms_debruijn.v
-equiv_debruijn.v
-subtype_debruijn.v
-context_debruijn.v
-morph_debruijn.v
-typing_debruijn.v
-eval_debruijn.v
-subst_lemmas_debruijn.v
+terms/debruijn.v
+terms/equiv.v
+terms/eval.v
+typing/context.v
+typing/subtype.v
+typing/morph.v
+typing/typing.v
+lemmas/subst_lemmas.v
 
-
-terms.v
-equiv.v
-subst.v
-subtype.v
-context.v
-morph.v
-typing.v
-smallstep.v
-soundness.v
-bbencode.v