Chore: Model relationships updated to make them simpler
Chore: Bill printing majorly refactored for it
Due to the sheer depth of the changes. There can be showstoppers. Please test it carefully
This will prevent printing all customer's names and phone numbers in the bill in case of simple walkins.
This is a breaking change as there is schema changes in the database.
It also bolds the customers who are to be printed in the bill in the running tables list.
