Merge branch 'upstream' into develop
Name boolean values in a boolean way

Uses isX, hasX or shouldX for boolean variables.
Name public boolean-returning functions in a boolean way

Renames methods to be "shouldX", "isX", or "hasX"
Chart.zoomable => Chart.setInteractiveAxis
Merge pull request #135 from tpkelly/develop

Name boolean values in a boolean way