tidy up a bit

- replaced deprecated `.contains()` calls with `.includes()`
- slightly reduced unnecessary `<<print>>` usage for variable variables
- removed and unset old npc variables from variables-versionUpdate.twee
- fix `:: Maths Library Student Seduce` to correctly check for a skirt
- disabled a check that had way too many false (and no true) positives
- re-indented everything with tabs and removed trailing tabs and spaces