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.

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); }