Fix: Check if file has been opened successfully on export

Change-Id: Idcae0fd9b3be7c72d260ab75987ab87f5f8026ac
pad with leading zeroes when writing to ostream and the date is less
than 2 characters

Change-Id: I70603fd68290fb9f1596a4145d1db3809729a96e
Implement load from file

Change-Id: Ie950064dee6b556f155568720464f79772af1222
Implement user friendly message when there are no entries in the list

Change-Id: I06a22c85b255c7f03e8113d8d327839ac8d42f0c
Implement PrintAllEntries menu entry

Change-Id: I19cdd7d20ba5da965fe7d7403dccfb5fb22d4246
Remove forgotten debug line

Change-Id: I2cbde8020e7dafbb6464d225b074c2650f961706
Does not allow duplicate faculty numbers

Change-Id: I5815c8bd60bca67b4f37375f0d19d2896af056c8