Option to close files belonging to single project

When a session have several projects, it will be very convenient to have right click on project and have an option 'close files in this project'. This will close all files that belong to the project that are currently open in editor.

This will be useful because often times there are common file names in each project (at the very least the mainwindow.h/cpp and framework classes) and it can be rather confusing to know which files is one operating in.

With this option, I can close all files in this and that project leaving only one project files open and than I know automatically the open files belong to that project.