Fix VarDecls for tuples. Closes #99.

I've implemented it this way since it doesn't require any changes in the
frontend. However, I think having TypeTuple expressed as LLVM struct types
would make much more sense and open the door to tuple lvalues.

tests/mini/tupleval.d

@@ -0,0 +1,30 @@
+module foo;
+
+template ParameterTupleOf( Fn )
+{
+    static if( is( Fn Params == function ) )
+        alias Params ParameterTupleOf;
+    else static if( is( Fn Params == delegate ) )
+        alias ParameterTupleOf!(Params) ParameterTupleOf;
+    else static if( is( Fn Params == Params* ) )
+        alias ParameterTupleOf!(Params) ParameterTupleOf;
+    else
+        static assert( false, "Argument has no parameters." );
+}
+
+struct S
+{
+	int opApply(T)(T dg)
+	{
+		alias ParameterTupleOf!(T) U;
+		U u;
+		u[0] = 1;
+		u[1] = 2;
+		return 0;
+	}
+}
+
+void main()
+{
+	foreach(int x, int y; S()){}
+}