Added new sequence tool:

    sequencetools.remap_sequence_by_range_pairs()

::

    >>> sequence = [9, 14, 4, 1, 7, 5, 9, 6, 2, 10, 15, 20, 8, 4, 0, 7]
    >>> range_pairs = [
    ...     ((2, 10), (3, 5)),
    ...     ((10, 20), (6, 8)),
    ...     ]
    >>> sequencetools.remap_sequence_by_range_pairs(sequence, range_pairs)
    [4, 7, 5, 1, 5, 3, 4, 4, 3, 7, 8, 7, 3, 5, 0, 5]