Add hysteresis to tooltip position

[ziebelje (Jon Z)]

You may find this update useful:

Tooltip Positioning (especially on mobile)

Getting this feature request going. Tooltip on charts especially on mobile can be a bit difficult to work around. From an email: One question: Is it possible to make the location of the data boxes optional–either fixed, draggable, or on one or the other side of the cursor? Currently, the data box almost always obscures the trend we are trying to examine–we have to move the cursor back and forth to get box out off half the data at a time