Complete implementation of the central star multiple sequence alignment algorithm.
This includes all the four major steps - pairwise alignment between all sequence pairs, finding the
central sequence, iteratively aligning the sequences to the gapped central sequence, and introducing
gaps in previous alignments during the iterative alignment.
The correctness of the implementation is verified by the Test_msa.test_central_star unit test of the
_lib._sequence_alignment.test_msa module.
