Fix sigma.js/issues/383
Added the "mouseWheelEnabled" setting

Setting it to false will prevent the mouse wheel to zoom in or out. This fixes #405.
fixed random colors in api-candy.html
Option to skip quadtrees indexation in refresh

From now, if you call `s.refresh({ skipIndexation: true })`, the quadtrees indexation will be skipped.
It is especially useful if you need the renderer to reprocess (with WebGL, for instance) but you have not changed any position related attribute (labels, colors, ...).
Fixes #397.
minor fix in WebGL renderer
Added defaultEdgeType & defaultNodeType parameters

BREAKING:
Instead of fallbacking to the default renderer when the type of a node, sigma will from now directly fallback the types of nodes and edges respectively to defaultNodeType and defaultEdgeType.
This makes it way easier to change the default nodes and edges renderers.
Also: Fixes #263.
Added scrollable-page.html example

This example is here to make it easier to test sigma in scrollable web pages.
"isDragging" flag from mouse captor in click event

The "isDragging" flag is true if:
 - Some "mousemove" events have been dispatched between the "mousedown" and the "mouseup"
 - There have been more than 100ms between these two events
Also, this fixes #342.
Fix to drag nodes in scrollable page works properly.
Merge origin/master