Text editor vertical lines on statements
This feature is now available as part of Visual Studio Productivity Power Tools. This is a free extension from Microsoft.
Productivity Power Tools 2013
Productivity Power Tools 2015
It comes bundled with a large number of other tools which you may or may not want. These features can be enabled or disabled in the Visual Studio options screen under Productivity Power Tools.
This is specifically part of the Structure Visualizer feature, which includes other sub features, such as code outlining in the margin, that can also be enabled or disabled individually.
Have a look at the indent guides extension, this can do what I think you want.