Made code for drop down reusable

WORKING
dropdown show by button

NOT working
added to last commit
Javascript for drop down

NOT yet complete
drop down shows courses
Co-requisites adding
Co-requisite Drop Down

WORKING
Editing Prereq

Don't know if it works
Powerpoint Presentations 1 & 2
Editing Prerequisite Finished

As well as validating if there is an $_GET['id']
merge