More vanilla

Story update

• New story: "The Chronicle of the Seal", six chapters from your first steps in the End to the defeat of the Enderite Boss
• Two characters, Orwen Valdraque and Nyssa, come to talk to you when a chapter begins
• Dialogue screen with an animated portrait, typewriter text and answer choices; the final choice changes the epilogue and your reward
• Cinematics with letterbox, fades and chapter titles (skip with Esc or by holding Shift)
• Story progress is saved per player; operators can use /more_vanilla story to test it
• Characters appear in front of you, in sight, on your side of a nearby portal and where they can walk to you; cinematics turn you towards what they show and keep their camera out of walls
• New animated, translucent texture for the Enderite Dimension portal