Checkmk Werk 7943: Fixed graph zooming via mouse wheel.

ID: 7943 Title: Fixed graph zooming via mouse wheel. Component: Multisite Level: 2 Class: Bug fix Version: 1.7.0i1 The 1.6.0 branch contained a regression which broke the synchronized zooming of graphs, you could even see JavaScript exceptions in the browser console while zooming. This has been fixed.