* Renamed normalise.cc' -> build.cc', `storeexprs.cc' ->

`derivations.cc', etc.
* Store the SHA-256 content hash of store paths in the database after
  they have been built/added.  This is so that we can check whether
  the store has been messed with (a la `rpm --verify').
* When registering path validity, verify that the closure property
  holds.

src/nix-store/dotgraph.cc

@@ -1,5 +1,5 @@
 #include "dotgraph.hh"
-#include "normalise.hh"
+#include "build.hh"
 
 
 #if 0

src/nix-store/dotgraph.hh

@@ -1,7 +1,7 @@
 #ifndef __DOTGRAPH_H
 #define __DOTGRAPH_H
 
-#include "storeexpr.hh"
+#include "util.hh"
 
 void printDotGraph(const PathSet & roots);
 

src/nix-store/main.cc

@@ -1,7 +1,7 @@
 #include <iostream>
 
 #include "globals.hh"
-#include "normalise.hh"
+#include "build.hh"
 #include "gc.hh"
 #include "archive.hh"
 #include "shared.hh"
@@ -187,7 +187,7 @@ static void opValidPath(Strings opFlags, Strings opArgs)
     createStoreTransaction(txn);
     for (Strings::iterator i = opArgs.begin();
          i != opArgs.end(); ++i)
-        registerValidPath(txn, *i);
+        registerValidPath(txn, *i, hashPath(htSHA256, *i));
     txn.commit();
 }