add faction base to the main shelter

[curstwist]

Summary

SUMMARY: Content "Allows the classic shelter to be a faction camp core building."

Purpose of change

Add more versatile faction camp locations.

Describe the solution

Made a shelter (the classic layout you usually start in) become the core/center for a faction camp. Includes palettes for rock, log, wood, wattle and daub, and standard t_wall.

Describe alternatives you've considered

I considered more wall types, but I think this is enough for now.
I also thought about adding additional kitchen items (smoking racks, etc), but you can expand into a kitchen building instead. Instead, I made the little craft/cooking area good enough for temporary use while you expand outwards.

Additional context

The layout once complete: This is just a simple level one kitchen, common area and bedroom building. You can use all the existing expansions around the shelter.

I didn't board-up/fortify anything since the player has greater control over that through the construction zones.

A sampler of the wall types. Pardon the mess.