Adds ability to define the minimal edge's arrow size.
release v1.0.3

Please read CHANGELOG.md to see what's new in this version.
Fix configForceAtlas2
Fixed nodes don't move when applying ForceAtlas2
Adding webglcontextlost listeners
Fix #371 - bug with hovers
Dropping `console.log` calls in HITS unit tests.
Nodes and edges can now have a number id
Fix #362
Introducting the renderers.snapshot plugin
Refining renderers.snapshot documentation
Changing behaviour of renderers.snapshot
Download is now optional. The function will now return the dataUrl so the user can deal with it.
Fix #403
It is now possible to instantiate a renderer by giving a string to the container parameter the same way you would with the constructor.
Dispatching an event when an instance is killed.
Fix #379 - someone can now bind a function on the 'kill' event in a plugin in order to die gracefully.
Fixing leak issues with non-worker ForceAtlas2
Fix #404 - thanks @dwalend.
Copy-paste error.
Merge branch 'master' into HEAD

Conflicts:
	src/renderers/canvas/sigma.canvas.edges.curvedArrow.js
fixed curvedArrows for #279
Merge branch 'master' into merge-pr-279
Merge branch 'master' into HEAD

 - Refactored hoveredEdges management as an object, to deal with the #371 issue, already fixed for nodes.
 - Adapted the arrow edges renderers to keep modifications from #279.

Conflicts:
	src/misc/sigma.misc.drawHovers.js
	src/renderers/canvas/sigma.canvas.edges.arrow.js
	src/renderers/canvas/sigma.canvas.edges.curvedArrow.js
Regenerated imports for plugin-snapshot example