* Add methods to remove and add items to a subgroup.
Add method to change the subgroup an item is in.
No longer decrement subgroup ID when removing a subgroup.
Fixes #2594

* Moved the orderSubgroups call outside of the add/remove methods.
Added the ability to call the add/remove methods without a subgroupId parameter (takes from item data instead).

Don't update the showNested property if nothing has been set in the data object, unless it is undefined.
Verify group object exists during `onGroupClick`

* Fix background items when orientation top

* Fix redraw order

* Fix error when option is not defined

* Allow template labels

* Add .travis.yml file

* Add experiment travis code

* Fix react example

* Fix events returned from mouse events

* Fix example

* Rename censor to stringifyObject in example

* Added support to supply an X2 to bar charts to have them scale

* Fixed graph2d stacking issue.  It no longer takes into account hidden items

* Changed x2 to end per recommendation and added this to the docs

This addresses #1982 and #1417.

It possibly reduces performance, but correctness seems better.

Clean up and centralise edit status for Timeline Items.

* Fix redraw order
* Fix error when option is not defined
* Allow template labels
* Add .travis.yml file
* Add experiment travis code
* Fix react example
* Fix bug in item editable

* Fix redraw order
* Fix error when option is not defined
* Allow template labels
* Add .travis.yml file
* Add experiment travis code
* Fix react example
* Make items z-index default to 1

* Fix redraw order
* Fix error when option is not defined
* Allow template labels
* Add .travis.yml file
* Add experiment travis code
* Fix react example
* Add animation to onUpdateTooltip

* change setCustomTimeTitle title parameter, Now could be an string or a function
* Fixed indent and spacing

* Fix redraw order
* Fix error when option is not defined
* Allow template labels
* Add .travis.yml file
* Add experiment travis code
* Fix react example
* Fix mousewheel while dragging item bug
* Return removed lines

Fixes default end, and reduces duplicated code. Adds tests.

* Fix redraw order
* Fix error when option is not defined
* Allow template labels
* Add .travis.yml file
* Add experiment travis code
* Fix right click button bug when dragging item

* Fix redraw order

* Fix error when option is not defined

* Allow template labels

* Fix #2538

- Also updated docs and examples for this
 - Fixed the positioning of the tooltip if groups was enabled
 - Removed missing parameters from Popup docstring

* Fix redraw order
* Fix error when option is not defined
* Allow template labels
* Fix boolean types bug
* Add subgroup stacking
* Almost finish subgroup stacking
* Play with examples for subgroup order
* Fix stacked subgroups
* Fix subgroup stacking
* Add stackSubgroups option
* Fix example
* Add docs
* Fix onRemove item subgroups recalculate
* Return subgroup example and add stackSubgroup example
* Split stackSubgroup example to subgroup/html and expectedVsActualTimesItems.html

* Added HTML tooltip support for Timeline

* Fixed tooltip position on Firefox

* Added Timeline tooltip example

* Updated tooltip location to be next to the mouse

* Added HTML element to example

* Fix groupEditable
* Fix group drag in vertical direction bug
* Fix indentation
* Add initial nestedGroups property
* Fix redraw order
* Get nested groups hiding working
* Add order to nestedGroups
* Fix up example
* Add support for intially closed nested groups
* Add nested groups indentation
* Fix indents
* Add nested groups docs
* Fix example
* Revert indents
* Add classes to nested and nesting group labels and add nesting group css
* Use pure css for nested group icons
* Remove commented off lines and unnecessary btn
* Fix indents
* Add support to showNested:false in group
* Add semicolon
* Remove empty lines

* Fix redraw order

* Fix error when option is not defined

* Allow template labels

* Fix redraw order

* Fix initial drag item bug

* Fix indents

* Fix redraw order

* Add initial itemVisibleFrame

* Add visibleFrameTemplate option

* Improve example

* Rename and fix example

* Fix comments from PR

* Fix example

* Add initial support for rolling mode
* Add rollingModeBtn and simplify example
* Make icon in css:
* Remove icon btn
* Add docs
* Fix zoom in rolling mode and initial start/end times

* Fix redraw order
* Fix calling dragStart mote than once

* Fix redraw order
* Fix IE10 support for dnd

* Fix redraw order
* Add elements censor and event to emitter
* Fix all recursive loop in json event
* Add docs for event emitted

* Add support to fixed times drag and drop
* Fix IE support for drag and drop
* Add support to IE pointer location and data setting/getting

* Fix groupEditable
* Fix group drag in vertical direction bug
* Fix indentation

* Fix mouse zoom on currentTime
* Fix customTime mousewheel bug

* Add hidden groups height calculations
* Fix jittering groups
* Remove non-existant parameter
* Cleanup example
* Remove console.log

* Fixed bug introduced in #2284 where overrideItems is set to true when boolean is provided
* Added the option of supplying object to item.editable with updateTime, updateGroup, and remove functioning similarly to timeline.editable but only on a single item
* Updated Documentation to reflect the new feature
* Updated the individualEditableItems example page to show feature usage.

* Timeline:
* Add overrideItems sub-property to timeline.editable
* Change behavior to override item.editable when overrideItems=true
* Added new example for timeline/editing to higlight differeing editable behaviors.
* Update timeline doc to reflect addition of timeline.editable.overrideItems
* Timeline - fixed logic oversights found in editable override testing
* Timeline - enable changeGroup when item.editable = true and not overriden
* Timeline - Small format changes to documentation and example pages for overrideItems

* 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