Favorite Documents extension lets you create links to frequently used code files and then quickly open them as a group or individually in Visual Studio 2010+.
v2.0 adds support for Visual Studio 2015; adds the ability to create favorites to external documents (pdf, doc), urls and programs; adds the ability to create favorites to classes, methods and class members. See the complete what’s new list.
https://tabsstudio.com/
Making Visual Studio perfect 