Update planned enhancements

[juliantayyc]

This pull request updates the docs/DeveloperGuide.md to include a detailed list of planned enhancements for future iterations, categorised based on:

1. Known Issues
2. Feature Flaws
3. New Features

The changes aim to provide a comprehensive overview of the application's current state and future development plans.

Known Issues:

• Help command popup window issue: On some platforms, repeatedly running and closing the help command in full screen may cause the application to hang or crash. The enhancement involves improving resource management and concurrency handling. (resolves [PE-D][Tester E] Running the help command multiple times in full screen causing the application to crash #183)

Current Feature Flaws:

• Overly general error messages: Error messages could be more specific to reduce user confusion. The enhancement involves introducing a more granular exception handling mechanism. (resolves Error message not specific enough #258)
• StudentID as duplicate detection mechanism: The current system relies solely on StudentID for contact identification. The enhancement suggests introducing a more robust identification mechanism. (resolves [PE-D][Tester C] Tutor also has StudentID #245)
• Filter command limitations: The filter command supports only one condition and has inconsistent matching behavior. The enhancement proposes adding support for multiple conditions and toggle features for AND/OR constraints and partial/full matching. (resolves [PE-D][Tester A] Filtering by courses does not match substrings #213, resolves [PE-D][Tester B] FIlter by multiple parameters not allowed #201)
• Index functionality: The current indexing is mainly visual. The enhancement suggests using indexes as an alternative form of contact referencing. (resolves [PE-D][Tester B] Allow commands to use index instead of just ID #209)
• Fixed role types: Only two role types are supported, and only one role is allowed per contact. The enhancement suggests implementing support for multiple role types, as well as customizable roles. (resolves [PE-D][Tester E] The role input for a person can be more versatile #210, resolves [PE-D][Tester E] Design issues with role feature #241)
• Fixed grading system Grading system currently follows letter-based system. Enhancement to include customizable grading system. (resolves [PE-D][Tester A] Expansion of grading system #199)
• Fixed Module utility Module utility can be made more versatile. Changes included added customizability.

New Features

• Undo command Allows users to revert the most recent change made to the application’s data.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

[ethan-goh]

LGTM