Multiple customTime vertical bars

- Added option to bypass default groups. If more groups are specified in the nodes than there are in the groups, loop over supplied groups instead of default.
- Added two new static smooth curves modes: curveCW and curve CCW.
- Added request redraw for certain internal processes to reduce number of draw calls.

Fixed the width problem for icons wich made it difficult to click on them

Add ability to use icon fonts for nodes

Add the ability to use icon fonts for nodes such as FontAwesome

Conflicts:
	dist/vis.js

- Added fontSizeMin, fontSizeMax, fontSizeMaxVisible, scaleFontWithValue, fontDrawThreshold to Nodes.
- Added fade in of labels (on nodes) near the fontDrawThreshold.
- Added nodes option to zoomExtent to zoom in on specific set of nodes.
- Added stabilizationIterationsDone event which fires at the end of the internal stabilization run. Does not imply that the network is stabilized.
- Added setFreezeSimulation method.
- Added clusterByZoom option and increaseClusterLevel and decreaseClusterLevel methods.

Still clustering bug and need more documentation on new features