Enrich sequence data passed between Forester and Jalview

With the integration of Archaeopteryx sequence data gets passed between Forester and Jalview at various points, such as when:

- Sending a tree calculated in Jalview to Archaeopteryx (Sequence data from Jalview --> Forester as the tree obviously originates from Jalview).

- Loading in an existing tree associated with a Jalview alignment that does not yet contain sequences itself. (Sequence data from Jalview --> Forester to fill in the tree sequences).

- Opening a new alignment from Nexus or PhyloXML files (Sequence data from Forester --> Jalview as Forester handles the actual parsing).

Only the actual amino acid sequence is currently passed along, this can be expanded quite a lot to include annotations etc.