added getDataSet to network manipulation edge add and edit functions …

Added  feature drawPoints.onRender

+ Checking for callbacks
+ Using the newly generated 'groupTemplate' object instead of group
+ Updated calls to DOMutil.drawPoint to use the groupTemplate instead of group

Timeline - editable option for individual items

Timeline will check for the property 'editable' on individual items.

  if editable === true
    ignore timeline option 'editable'
    allow item to be edited
  else if editable === false
    ignore timeline option 'editable'
    do not allow item to be edited
  else
    use timeline option 'editable'

If two items are selected and one is not editable, only the editable
item is draggable.

This change required the css class .vis-editable be moved from the
item set to the individual item containers to maintain proper styling.

Core.prototype.fit and Core.prototype.getDataRange fixes

+ according to the documentation
+ changed from 'start' and 'end' to 'min' and 'max'

+ instead of returning 'null', returning the
  calculated values