sensible behaviour for group file drags/opens

Its nice to be able to drag a whole directory or bunch of files into Jalview and for it to do sensible things, e.g.:

Load all alignments into the same dataset.
Load all feature files onto the sequences in the new dataset.
Load all trees onto the dataset or the (single) alignment ? (Note - vamsas relationship that Jalview doesn't yet support)
Find best association for all structures onto sequences in dataset
Most difficult: load annotation onto most appropriate alignment (need an alignment reference of somekind, or could use file name root).