Change the keys for `Game.map.describeExits` to be actual directions

[tiennou]

Brief Description

This makes it at least a bit clearer why the keys are odd numbers.

Checklists

• [x] Test passed
• [x] Coding style (indentation, etc)
• [x] Edits have been made to src/ files not index.d.ts
• [x] Run npm run dtslint to update index.d.ts