sequence fetcher update

Hi All.

I've just checked in a modification to the Jalview sequence fetcher - so
you can now query DAS sources that support the sequence command. This is
highly experimental - let me know if you have any odd behaviour or
problems (that aren't related to the DAS sources themselves... ).


pps. The PFAM fetcher is still broken - I'm waiting for a recommendation
from the PFAM team concerning the correct retrieval mechanism to use now
they have a new SOAP API.

Hi All.

PFAM alignment retrieval has now been fixed in the development version
of the Jalview Application.