Tests to define LoadCourseModule usage
adding "load course module" cmd to textui

without the actual functionality, though
fileHandler moved to TextUIController
IT'S EVEN MORE ALIVE! implemented loading json cmd

now loads json dump with "load course module (path)" into ArrayList of
CourseModules

TODO: integration with List<Activity> activities so that "view
activities" views also course module activities?
View command shows the activities of loaded module
updated view week to support course modules, too

via new convenience method for CourseModule,
described new functionalities in README

also, a picture of textui!
Merge branch 'implement-json-reading-in-text-ui'

CourseModule loading related textUI features mostly implemented, so
wrapping up this topic branch.