Added an interface function for Calendar creation
Using the calendar interface to create the calendars
Added test to visualize calendars
Added test for visaluzation of booked slots on calendars
Necessary change from ⎕⌹ to OX for visualization to pass through TCP Socket
The server supports visualization requests for a calendar based on name 'show ${BOOKABLE_NAME}'
Now able to show multiple calendars 'show [${BOOKABLE_NAME}]'
Modified calendar slice to take actual calendar datastructure
Added handling for case when could is empty set for all must