Class system rework

- Different male scientists (thanks to OOD from SL Blender community)

- Add support for different skins

  - All humans

  - Skins can be either randomized or single, the latter is useful for SCPs (SCP-131 will use this).

  - SCP-023

  - SCP-131

  - SCP-173

  - SCP-347

  - SCP-650

  - SCP-939

- Re-implemented season outfits and remove legacy system from `BasePuppetScript`.

- Ragdolls were replaced with short-lived silhouettes.

New and reworked SCPs

- SCP-080

- SCP-1507 (tied to a variation of Class-D)

- Added second variation of SCP-131 instance

- Optimized SCP-347 (which allowed to reintroduce in Lite/Web version), removed legacy mechanics completely and gave her a room (finally after a year of wandering)

- [Christmas] Fixed SCP-649 - increased cold damage and refactored snow spawn, making it easier for programmers to implement.
Maintenance Zone expansion

- Import some open-source rooms from SCP Echoes, that fit the game style.

- Different door frames in Maintenance Zone
### Game progress system/achievement

- Added achievements for studying SCPs (not necessary the task one, and not all SCPs)