KenChat v0.1 Level 7

A task managing chatbot with the following functon:

1. ToDo - adds a ToDo task to the list
2. Deadline - adds a Deadline task to the list, to be completed by a date and/or time
3. Event - adds a Event task from a start date and/or time to a end date and/or time
4. List - Lists all the recorded tasks.
5. Mark - Marks a specific task (usually when the task is completed),
6. Unmark - Unmarks a specific task.
7. Delete - Deletes a specific task from the list.