Fixed ModuleInfo generation to no longer use the ModuleInfo class' default initializer for types/defaults, it's unsafe as initializers don't necesarily match the "formal" type. There might be explicit padding. Changed -g switch to emit DW_LANG_D debug info, make demangling work with a patched GDB, still more work to do for full support of D's Dwarf extensions. Added getNullValue helper method.

--- a/gen/tollvm.h	Sun Nov 30 20:41:17 2008 +0100
+++ b/gen/tollvm.h	Mon Dec 01 02:10:16 2008 +0100
@@ -87,6 +87,7 @@
 const LLPointerType* getPtrToType(const LLType* t);
 const LLPointerType* getVoidPtrType();
 llvm::ConstantPointerNull* getNullPtr(const LLType* t);
+LLConstant* getNullValue(const LLType* t);
 
 // type sizes
 size_t getTypeBitSize(const LLType* t);