Move position into Creature

[eltank]

Summary

Infrastructure "Move position into Creature"

Purpose of change

The position field and related getters and setters are duplicated in Character and monster, the 2 subclasses of Creature.

Describe the solution

Remove the duplication by moving the code into creature.h. Also position is now protected.
Monster, Character and npc still override setpos() in order to do other stuff, but now they call the superclass' setpos() instead of modifying the position directly.

Describe alternatives you've considered

Going one step further by making position private. Would need to fix many references to use pos() instead.

Testing

For the save/load code: loaded an existing save made prior to the change, got no errors. Spawned a monster and an NPC, saved and loaded again to verify they didn't teleport.

Additional context

[eltank]

Forgot to update the save/load code, done now.

[anothersimulacrum]

#42291

[eltank]

#42291

I am aware of the location class. Are you suggesting moving the implementation there? I got the impression that it's meant to be a pure virtual class.

[anothersimulacrum]

Sorry, I should have left a comment, just wanted to make you aware of it if relevant/link the PRs together.