add an explanatory comment about the different types of jbrowse pub/sub messages
rename message /jbrowse/v1/v/tracks/changed -> /jbrowse/v1/n/tracks/visibleChanged
implement track deletion and config editing in the track menus
bugfix to genomeview track order when editing track config
make the Simple tracklist listen for and act on track edit and delete commands
tweak title of config menu item in track menus
little bugs
need to update grid selections in the faceted track selector in response to track on/off events
add support for track deletion to faceted tracksel
in track config editor, put in an empty metadata hash for convenience
add support for track adding to faceted tracksel
fix track editing in faceted tracksel
add support for BigWig file adding
refine BAM filedialog tracklist driver a little
polish file-opening box a little more, adding a help message and some mouse-hover cues to encourage people to add files and urls
Merge branch 'add_files' into jbrowse_1.7

Conflicts:
	tests/js_tests/index.html
Merge branch 'maint/1.7.x' into jbrowse_1.7
Merge commit 'd13a9f2bb9e031421e1e9d44bd3e0c63e316ab88' into jbrowse_1.7
add a filedialog tracklist driver for gff3 files.  file dialog now tries to use a JBrowse/Store/SeqFeature/GFF3 module that does not exist yet.
flesh out GFF3 backend stub so that it runs (but returns no data of course)