Feature - Filters on classes

## Add filters so that a user-input term can result in subsets of information to be printed
Interacts with data structures holding all classes and allows certain classes to be printed.
### Requirements
- Prompts user to enter if they would like to use a filter
- Doesn't allow undefined filters
- Directly/Indirectly interacts with the structures holding all the class info
- Simple for user to use through terminal
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