Changeset [06dc2f3547a3994e1b876aa4402551091790ccfb] by Robert Buels

Fixes #216, fixes #217:

issue #216: Navigating via sequence dropdown selection ignores
previous location on selected sequence, whereas with navigation text
box entering just a sequence name navigates to previous location on
that sequence (if visited previously).

issue #217: Initial default view of previously unseen seq starts at
80% centered view, but any use of seq pulldown takes it to 100%

Cherry-picked from Gregg's d19bbd8a59d73f3e0dc784b3452fafbe9b65e95c

Conflicts:

src/JBrowse/Browser.js

https://github.com/GMOD/jbrowse/commit/06dc2f3547a3994e1b876aa44025...