Add richer notifications; notify on point removal as well
Update the currentSample pointer when drawing
Ignore null points when rendering
When deleting points, just make the values null in pointArrayIndexed

... and then strip the null values when copying to pointArray.
Specify which line should be the one to draw on

This will be useful later with multiple data sets.
Fix autoscale bug - only autoscale if 1 or more points exist
Fix bug in dragging x-axis while drawing
Quit drawing if we leave the graph during a drag

[#76561416]
Fix drawing of annotations in Safari and IE

ParentNode.children is only supported in Chrome and Firefox

[#83155888][#74688264]