Module Planner should be better at recognizing equivalent modules for fulfilling prerequisites

[nighoggDatatype]

Describe the bug

Right now CS2100, CS2030, CS2040S and probably many other modules do not recognize certain modules as equivalent for the module planner. Specifically, it does not recognize CS1101S as an equivalent module for the purpose of prerequisite.

To Reproduce

Steps to reproduce the behavior:

1. Go to module planner tab
2. Add CS1231S and CS1101S to Year 1 Sem 1.
3. Add either CS2100, CS2030, or CS2040S to Year 1 Sem 2
4. Note that CS2100, CS2030, and/or CS2040S complain that CS1010 has not been taken first

Expected behavior

The expected behavior is that CS1101S fulfills the prerequisite for CS2100, CS2030, and CS2040S in lieu of CS1010.

[ZhangYiJiang]

So this is generally not possible automatically because we simply lack the data to make an accurate determination. It is in theory possible to deploy some heuristic, like stemming the module code when looking at prerequisites, but that's not necessarily safe, and we prefer to be conservative with our assumptions about the data.

We can also just let users override warnings and waive requirements, but you can already sort of do that by adding the equivalent module that's present on the module's prerequisite to the list of exemptions. In your case you can add CS1010S or CS1010 to your list of exemptions - that module should be present on CS2100's list of prereqs. Exemptions don't count towards module credits or are used for exam clash so they are safe to use.