`line-blur` isn't affected by devicePixelRatio now

fixes #615
Remove unused parameter
much more natural panning inertia, close #619
more inertia comments
adjust inertia params
limit max inertia speed
more predictable inertia velocity
Merge pull request #625 from mapbox/inertia

Much more natural panning inertia
Don't share code between background and fill

Not worth the added cyclomatic complexity.
Remove tileSize constant from Map
Delete commented out code
Fix tileSize reference
Eliminate painter.bufferProperties
bump pbf and vector-tile with fix for doubles

ref #626
Calculate position matrix like native (#627)
Use mat4.create()
bump
setPosition -> setView

To match Leaflet, and because "Position" has too many other
connotations.
Merge pull request #633 from mapbox/setView

setPosition -> setView
Remove scaleTo (fixes #634)