Fixed weird struct problem from downs, see mini/compile_structs1.d Rewrote DtoIndexStruct/Class , the old implementation were way too complex for what we really need now - since the DotVar changes.

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);
}