Avoid doing the clipping instructions manually.
This pull request is an application of #1097.
This pull request allow to save about 200 lines of codes (only for clipping).
And fix a little issue with points symbol that overlap plot borders.
Cleaning drawing instructions
Avoid do clipping instructions manually.
Thank you for the submission, but unfortunately clip is not supported by excanvas, which means that this won't work on IE7/8. We need to clip manually until their market share is low enough that we can stop supporting them. I'd guess that is still at least a year or so away.