[CDF-306] - CCC - Lines with a single null-valued series fail to highlight correctly when hovered-over.
* Fix line hovering not working well.
   A new option, the pointingMode, allows choosing between "fuzzy" pointing and normal over event.
   Default is the fuzzy behaviour.
Merge pull request #110 from dcleao/CDF-306

[CDF-306] - CCC - Lines with a single null-valued series fail to highlight correctly when hovered-over.