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.

module typeinfo13;

void main()
{
    float[long] aa;
    auto ti = typeid(typeof(aa));
    assert(ti.toString() == "float[long]");
    assert(ti.next() is typeid(float));
    assert(ti.tsize() == size_t.sizeof);
    auto aati = cast(TypeInfo_AssociativeArray)ti;
    assert(aati.value is typeid(float));
    assert(aati.key is typeid(long));
}