Sketch of function to group fonts by families.
default to screen resolution to calculate tile size
ghost label consistency
Prep font command for rendering family names.
full width toggles were weird
Update font fixture.
add tile scale param to source tiles
Cache fontfamilies tree gen which is not cheap.
Group fonts into collapsible family panes. Refs #498.
add route for non-retina
Merge pull request #502 from mapbox/fix-retina-xray

add tile scale param to source tiles
Merge pull request #501 from mapbox/autoscale-print

default to screen resolution to calculate tile size
Merge pull request #503 from mapbox/font-families

Collapsible font families
Merge branch 'master' into source-raster
Let _image layername be internal to tilelive-vector and establish raster_local as default raster layername for local sources.