Uses kClust to generate clusters of amino acid sequences.
:param sequences: All sequences you want to cluster.
:type sequences: :class:`ost.seq.SequenceList`
:param clustering_thres: Sequence identity threshold to build clusters. Note,
that clustering_thresh is more a rule of thumb, since
compositional bias in the sequence can also play a role.
The value gets transformed in a bitscore, that is used
as an input parameter of kClust
:param create_alignments: Flag, wether the alignments of the clusters get calculated.
Requires clustalw in the path.
:returns: A list of cluster instances
:raises: :class:`~ost.settings.FileNotFound` if kClust could not be located.