Merge pull request #177 from tcarver/master

misc
Merge pull request #178 from tcarver/master

misc
Merge pull request #179 from tcarver/master

misc
Merge pull request #180 from tcarver/master

use uniprot.org for protein links
Merge pull request #181 from tcarver/master

misc
rework GFF3 export code
make mapped character list public
add test for GFF3Encoder
add tests for GFF3AttributeBuilder
remove obsolete comment
make aggregators tied to pre-mapping keys take precedence
Merge pull request #3 from satta/gff

Changes in GFF3 export