Wrapping RelabelLabelMapFilter

Change-Id: Ic933f7544e00302e4b83a156fbe443c22e1f4b58
Wrapping AggregateLabelMapFilter

Change-Id: I304b8091d9938a37e1127e7c4bb2ca8714f54a51
Merge topic 'SIMPLEITK-512_AddLabelMapFilters' into next

4cdf9d34 Wrapping AggregateLabelMapFilter
30746049 Wrapping RelabelLabelMapFilter