aggregate summary annotation on reference sequence

Often, the reason for a reference sequence identification being specified on an alignment is that it is of special interest in the sequence analysis task being undertaken. In that case, Jalview should enable summary annotation to be appended to the reference sequence that conveys information garnered from the alignment. This could be:
* consensus, conservation, variation or other kinds of sequence profile information derived directly from Jalview's own calculation routines.
-> mutations could be encoded as variant features using standard ontology
-> consensus/conservation/logo tracks become sequence associated but are also dynamic, should the alignment be later edited.
* annotation transfer: features and/or annotation tracks on other sequences could be processed and a set of summary 'parsimonious' annotations added to the reference (along with a likelihood score).