[svn r183] Fixed broken identity expressions with two pointers of different types. Fixed broken pointer arithmetic for subtraction (tango.text.Util unittest now passes)

module nested9;

void main()
{
    int i = 42;
    int func()
    {
        return i + 1;
    }
    int j = func();
    printf("j = %d\n", j);
    assert(j == 43);
}