Rite of Returning 1.0.63

Rite of Mortal Severance is now an active staged ritual:
- Shadow/tentacle infection builds over 3 minutes.
- Player receives: "Be prepared to fight the curse of souls"
- At build completion, the player becomes mortal again and Cursed Soul spawns.
- Cursed Soul is a 3-block-tall wither skeleton with a diamond sword, 100 health, iron-golem-like speed/damage, and 3 full-health revivals.
- After final Cursed Soul death, the infected blocks deconstruct back to their original blocks over 3 minutes.
