Publish the default visuals as open source custom visuals

[mstacey]

A lot of (reasonably) basic settings on the default charts are missing - for instance gridlines across the chart area for x-axes the way y-axes can be enabled. Instead of trying to support each and every version of this scenerio, publish and maintain each of the default chart types on GitHub so that we can simply use them as a base for further enhancements and quickly add simple features without having to develop the charts from scratch