…"MyDuke" that consist of all the methods/abilities of Duke

… description]

…s, Deadlines] , together with the usage of switch statement and enum

… implementation due to problems during exception handling on enum

…dded DukeFileOperation class for file related operations

…ad file in the right way

# Conflicts:
#	src/main/java/Duke.java
#	src/main/java/myduke/MyDuke.java

# Conflicts:
#	src/main/java/data/duke.txt
#	src/main/java/myduke/MyDuke.java
#	src/main/java/myduke/task/Task.java