ee8fd1e613
Currently both the base classes for messages/sections and the message list itself that instantiates the available sections are located in the same module. As a result, it isn't possible to define sections in a different module without introducing circular dependencies. The Calendar module is already unwieldily large, so split it up a bit to avoid it growing even bigger in the future. https://bugzilla.gnome.org/show_bug.cgi?id=756491