Use requestAnimationFrame to throttle redraws

* 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

* generate individual css files; fixes #1969
* simplified css bundleing
* add new generated dist-css files
* use chart specific css files in the examples

* 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

* removed everything build related
* added keywords because it is recommended

* replaced deprecated gulp-minify-css with gulp-clean-css
* updated mocha

* Added getBaseEdge, getClusteredEdges updateEdge and updateClusteredNode to allow option changes of the clustered edges as they are no longer the original base Edge

changing edge color is a good example.
i.e network.clustering.updateEdge(originalEdge.id, {color : '#aa0000'});
will now update all edges including the ones that were created when clustering.

Also when clicking on a clustered edge the event returns the clustered Edge id, which doesn't mean a lot.
This can be now converted back into the original edge with
network.clustering.getBaseEdge(clusteredEdge.id)

Similar with updateClusteredNode
This new method allows the options to be changed on a clustered Node.

i.e clicking on a clustered node gives its clustered node id.
Want to change the clustered image to a star then do this
 network.clustering.updateClusteredNode(clusteredNodeId, {shape : 'star'});

* Updated docs with getClusteredEdge, getBaseEdge, updateEdge and updateClusteredNode

Also added method subsections into contents

* Added better error handling to updateEdge and updateClusteredNodes

corrected errors spotted by @mojoaxel

* Added example html demonstrating getBaseEdge, getClusteredEdges updateEdge and updateClusteredNode

* Added getBaseEdge, getClusteredEdges updateEdge and updateClusteredNode to allow option changes of the clustered edges as they are no longer the original base Edge

changing edge color is a good example.
i.e network.clustering.updateEdge(originalEdge.id, {color : '#aa0000'});
will now update all edges including the ones that were created when clustering.

Also when clicking on a clustered edge the event returns the clustered Edge id, which doesn't mean a lot.
This can be now converted back into the original edge with
network.clustering.getBaseEdge(clusteredEdge.id)

Similar with updateClusteredNode
This new method allows the options to be changed on a clustered Node.

i.e clicking on a clustered node gives its clustered node id.
Want to change the clustered image to a star then do this
 network.clustering.updateClusteredNode(clusteredNodeId, {shape : 'star'});

* Updated docs with getClusteredEdge, getBaseEdge, updateEdge and updateClusteredNode

Also added method subsections into contents

* Added better error handling to updateEdge and updateClusteredNodes

corrected errors spotted by @mojoaxel

* Added example html demonstrating getBaseEdge, getClusteredEdges updateEdge and updateClusteredNode

code cleanup;

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

Resolve issue #1857 Fixed node positioning with improvedLayout:true

Improvements for graph3d legend support

Fix incorrect documentation URL

Perturbing the nodes was being performed on all nodes regardless of whether they were set as fixed.

fix known security issue with handlebars version