[svn r27] * Fixed bug in aggregate field lookup.

* Fixed structs with no fields.
* Added support for NegExp as in -x.

test/bug1.d

@@ -0,0 +1,5 @@
+module bug1;
+struct Foo { Foo opSub(ref Foo b) { return Foo(); } }
+struct Bar { Foo whee; }
+void test(ref Bar moo) { Foo nngh; auto plonk = nngh - moo.whee; }
+void main() { Bar bar; test(bar); }

test/neg.d

@@ -0,0 +1,13 @@
+module neg;
+
+void main()
+{
+    int i = 32;
+    long l = 55;
+    float f = 23;
+    double d = 4;
+    assert(-i == -32);
+    assert(-l == -55);
+    assert(-f == -23);
+    assert(-d == -4);
+}