Make genome selection dialog wider

IGV-2069 , item 1)
Have the genome selection dropdown be wider than the combo box

Will be as wide as the widest element (ie longest genome)

IGV-2069 , item 2)
Refactor SearchCommand

Build tokenMatchers statically, once, instead of on each search
When a single base is provided as a sort argument, auto-sort by base

IGV-2064
webstart.js:  use http protocol to launch IGV when possible
Log error when byte-range is requested by Content-Range header is missing from the response
Merge remote-tracking branch: upstream/master