update copyright year to range
Fine tuning on existing captors

The issue was visible on the examples/force.html sample: If the mouse was over a node, the hovered node was staying hovered as long as the mouse does not move.

The problem was that I removed earlier the event binding to the render event. It is restored, and the touch captor il now dispatching the "mouseMove" event, to fix the bug I tried to fix when I removed the binding...
Avoid using 'for in' to iterate over arrays.

'for in' also iterate over additionnal attributes set on the Array prototype, leading to unexpected
behaviors.
To make sigma.js more defensive against third-party libraries modifying the Array prototype, a more
classic way of iterating is required.

This patch solve issue #183.
PR #185 did not pass closureLint: Minor renaming

Just renamed max values in new "for" iterations to keep lines under 80 chars.
Minor fix on GEXF parser plugin

Same bug as the one previously fixed in the JSON parser:
When the parser was called with only a path and a callback, the callback was never called.
Fixed ForceAtlas2 stopForceAtlas2 method

When the stopForceAtlas2 method was called, a final step of the algorithm was called later.