Refactor SIGSET.__repr__() to call other methods

[wdoekes]

def __repr__(self):
    human_sigs = _get_human_signals()
    return '{%s}' % (', '.join(ret),)

def _get_human_signals(self):
        ret = []
        for i, bitmask in enumerate(self.val):
            if bitmask:
                ret.extend(self._get_XXX(mask2list, i, bitmask)
    return ret

def _get_XXX(...):
                if mask2list and i <= 1:  # 64 bits in the first two int32s
                    numbers = mask2list(bitmask)  # sorted from low to high
                    if i == 1:
                        numbers = [i << 1 for i in numbers]
                    for number in numbers:
                        ret.append(SIGNAMES.get(number, 'SIG%d' % (number,)))
                else:
                    strvalue = binrepr and binrepr(bitmask) or str(bitmask)
                    ret.append('%d: %s' % (i, strvalue))
    return ret

Or something..