Initially, the default section title was swapped within the course format
javascript functions. Though some section titles may be custom and does not
require swapping, in addition they may have links to single section view. This
introduces some callback functions for define what needs to be done in
sections libs and js files.
This library handles registration and invocation of calls for other
libraries. It allows us to register javascript modules containing functions
which may called dynamically later on, for example when adding a resource
or section dynamically