* Removed restriction to allow clusters of a single node; Default functionality remains the same;  Also added new example
* Add documentation for allowSingleNodeCluster, and removed excessive cluster() calls in example.
* Changed documentation as per request.

* 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

Networks are exported as a JSON array containing an array of objects representing each node in the network. Each node contains an Id, it's x and y coordinates and the nodes it is connected to.

Import converts the JSON to a vis DataSet and then regenerates the network using each node's attributes, inserting it in the same coordinates and with the same number of connections as before.

fixes #2073

* 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

* Add the source data to Point3d objects in Graph3D; This allows more complex tooltips, using information sent from the server + the source object
* Update PR as requested
* Convert tabs to spaces; Vim config was off, edited in sublime instead

* 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

* 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

Added a "showLegend" option which can be used to toggle legend drawing
Added legend drawing to 11_tooltips and to playground examples
Added description of showLegend option to documentation

- Added parentCentralization option for hierarchical layout.

unified border calculation. Needs to be centralized to avoid duplication.

added example. Improved handling of options for hierarchical view.

See https://github.com/almende/vis/issues/1568#issuecomment-171961393

- Fixed #1528, #1278, avoided ID's being cast to string for methods that return ID's as well as storePositions casting to string.

Separate shading from line drawing (fixes drawing order)
Cleanup of draw code
Fix icon-shading CSS override

- unified some methods in the networkUtil
- Fixed initial zoom issues #1252