Interfaced with Next/Previous Buttons
Added functionality to the Next/Prev buttons
Edited displayInfo()
Added method to retrive material class
Modified for playSound issues
Added comments and hides playSound when the display Record is for a book
Corrected for display the sound button
Merge branch 'master' into Mark
Javadoc started, added exception handling for default constructor
Javadoc started, minor edits to layout.
Javadoc added, edited comments
Merge branch 'master' of https://github.com/rustadmd/OOLibrary

Conflicts:
	OOLibrary/src/oolibrary/Librarian.java