* Important performance enhancement supporting incremental changes to large graphs, these were too slow due to doing a full item conversion on each add().
Note: the data handling side of graph2d is currently somewhat over-engineered (=too complex) It can use some simplification....

* Fixed style based on feedback.

* Add initial onChange item tooltip
* Add example and tooltipOnItemEdit template option
* Add docs and rename option
* Fix docs
* Fix example
* Change example's item types
* Fix point item tooltip
* Fix comments from PR and support bottom orientation properly
* Add semi-colon

@simo9000 Thanks!

* Add initial experiment
* Register drag and drop events
* Add initial drag and drop support
* Add drag and drop support for all types of objects
* Fix example
* Clean up code and add comments
* Fix example
* remove font awesome
* Fix example style
* Add meta tag to example and add selected when dropped

* Hide vertically hidden ranged items in groups that are not visible
* Add element to templates options
* Fix comment typo
* Add documentation for react mounting
* add react example
* Fix typo
* fix title
* Fix review comments
* Add vis-drag-center to fix dragging bug when template is react component

* Hide vertically hidden ranged items in groups that are not visible
* Add element to templates options
* Fix comment typo
* Add documentation for react mounting
* add react example
* Fix typo
* fix title
* Fix review comments

* Add initial scroller without options
* Add initial scroll without an option
* Add verticalScroll option
* Fix scrollbar positions
* Add docs
* fix example
* remove jquery dependency
* Fix example
* Fix review comments

* Hide vertically hidden ranged items in groups that are not visible
* Fix misspelling
* Fix examples that do not contain groups
* Add example for vertical hidden ranged items
* Fix indent format in RangeItem
* Fix example
* Fix other examples after addition of vertical hiding range items in groups
* Add case of zero margin axis
* Fix commented out lines in examples
* Fix vertical visibility bug

* Hide vertically hidden ranged items in groups that are not visible
* Add element to templates options
* Fix comment typo
* Add documentation for react mounting

* Hide vertically hidden ranged items in groups that are not visible
* Add custom function format for time labels
* fix misspell
* remove spaces
* remove backspace
* add backspaces
* Add docs and examples
* Fix docs

* Hide vertically hidden ranged items in groups that are not visible
* Add rtl to timeline options docs
* Fix misspelling
* Update RangeItem.js

* fixes #2092

* fixes #2064

* Hide vertically hidden ranged items in groups that are not visible
* Fix misspelling
* Fix examples that do not contain groups
* Add example for vertical hidden ranged items
* Fix indent format in RangeItem
* Fix example
* Fix other examples after addition of vertical hiding range items in groups
* Add case of zero margin axis

Add flag to check whether an item in the Itemset is currently being dragged

It was broken by PR (#1729), which fixed issues #112 & #1730.
As far as I can tell that change shouldn't influence the DataAxis (vertical-axis), but only the horizontal axis.

 @yotamberk can you check if your examples still work as expected?

Internet Explorer does not support the ES6 Number.parseFloat (see http://caniuse.com/#feat=es6-number). Instead, substitute the regular parseFloat method.