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 classes7;

class C
{
    int i=0;
    void f()
    {
        i=42;
    }
    void g()
    {
        f();
    }
}

void main()
{
    scope c = new C;
    c.g();
    assert(c.i == 42);
}