Shift fiddling with `ModulesSelectedOrder` and Exam Timetable outside `add-module-lesson-group!`
Shift fiddling with `ModulesSelectedOrder` and Exam Timetable outside `add-module-lesson-group!`

In preparation for adding modules without any lessons to
`document.location.hash`.

Signed-off-by: Pang Yan Han <22594c345857f664c61cd411f607c4d40a9d4af9@gmail.com>

yanhan/cljs-nusmods,yanhan/cljs-nusmods,yanhan/cljs-nusmods