Added IrTypeFunction and IrTypeDelegate and eliminated IrDType. This means the Type::ir field can be removed. It's the final part needed for the move to a slightly more sane type system. Now the whole thing just needs to be cleaned up :P

Added -v-cg switch, which right now just prints "codegen: module.name (module/name.d)" to stdout, this can really help figuring out where, in some complex build command, things go wrong.

dmd/module.h

@@ -28,7 +28,7 @@ struct Library;
 
 // Back end
 #if IN_LLVM
-struct Ir;
+class Ir;
 struct DValue;
 typedef DValue elem;
 namespace llvm { class Module; }