Ensure Graph creates a copy of the x/yScale before modifying it

x/yScale is coming from the configuration dictionary which may be
referenced by the Graph creator, or shared with other Graphs. We need to
ensure we copy the scale so that our mutations do not change the object
given to us.
support resizing preview range sliders; closes #375; closes #417; closes #382
add x magnitude scale and improve barWidth calculation for bars renderer
use preview range slider in multi renderer example
refactor lineplot to work with multi renderer; closes #413; closes #414
Merge pull request #387 from dwt/clone-mutable-xscale

Ensure Graph creates a copy of the x/yScale before modifying it
update built libs
Update README.md
Merge branch 'master' into wormly