Dissection task and bug fixes

[eamathie]

• What kind of change does this PR introduce?

  • Feature and bug fixes

• What is the current behavior?

  • The salmon dissection task is not yet implemented, so the NPC's dialogue resets when this task is chosen (Implement dissection task #862 and Create system for dissecting salmon and highlighting organs #847)
  • NPCs sometimes stand still like a statue when at a branch point in its dialogue (NPCs standing still like a statue #867)
  • The NPC's exit and skip line buttons sometimes do now show up (NPC dialogue box exit and skip buttons not showing properly #868)
  • Duplicate salmon sometimes spawn in the laboratory when task structures/objects reset (Duplicate salmon sometimes spawn in laboratory #869)

• What is the new behavior?

  • The salmon dissection task is fully functioning, with task structures for the tablet, a dissection system, and a mesh highlight system, and a new salmon 3D model for the dissection task
  • NPCs tend to stand rigidly still a lot less
  • The NPC's exit and skip line buttons now show up
  • Duplicate salmon no longer spawn in the laboratory when scene resets

• Does this PR introduce a breaking change?

  • Unlikely, but there are changes to the NPCs which may cause minor conflicts with the AI NPC branch.

• Other information?

  • I removed the step of requiring the fish cage (fishmerd) model in README.md

[OlaBekkevold]

Everything works as it should. But I discovered that if you try to start a task in the laboratory while the NPC is already standing at it's destination for the task, the NPC will just restart the dialogue and the task never starts. But this is probably a general issue and not specific to this pull request.