Bunch of misc fixes today for build 442:
- Slug quest – now pops up a reminder when the five slugs are slain to go back and talk to NPC
- A little reminder at the bottom right of dialogs to press E to advance/close them
- Intro sign now references WASD instead of Arrow Keys (much more ergonomic). E also refers to use/npcs instead of reading signs
- Slugs should no longer float suspended in space sometimes
- Slugs no longer target dead players
- Extra error handling and crash prevention in quest system
