etc.
Found a few edge cases where errors happen. Creating nv.utils.NaNtoZero()
function, to be used in places where points and lines are rendered.
Using NantoZero in scatter.js and interactiveGuideline.
interactiveGuideline logic. This function is used to find the x point
position given a mouseX location. It's a more robust solution. Made sure
chart tests passed.
