Spectre Creep

Added entity Viggo and Felix (just one entity with two faces)

Viggo and Felix is invisible until being close to the player.

Added Creep Runners that spawn naturally that simply run away from the player unless an actual Creep spawns in the area.

Parasitic Maggots now have a chance to infect the player.

Spectre has a new model and texture.

New gamerule Disable Ghoul disables Viggo and Felix

New entity Murk Lurker that attacks other horrors and is also neutral. Spawns in Lush caves, Mangrove swamps, and swamps.

Spectres now leave ghost versions of themselves when they die. If another Spectre doesn't spawn in about a minute, the ghost will turn into a Spectre.