Rapid Evolution for 3.7+

Inspired by a suggestion by Marble in the Stellaris Modding Den, this mod causes presapient species to randomly spawn and develop sapience. It also increases the variety of presapient species portraits at the expense of decreasing their typical quality. Presapient Spawning New pre-sapient species will sometimes spawn at random at a rate scaling with the "Primitive Civilizations" game setting and galaxy size. This spawning rate will be lower on highly developed planets with weak environmental protections. In an empty medium-sized galaxy with 1x primitives, on average one presapient species will spawn every 80 years. With Lithoids, presapient species have a roughly 4% chance to be Calamitously Born, with the associated planet modifiers; if this happens on an inhabited planet, the effect will first trigger the Asteroid Sighted event chain and the presapients will spawn only if the asteroid hits. Developing Sapience Pre-sapients will sometimes spontaneously evolve sapience. The length of time this takes for each species is random, and the average depends on the "Habitable Planets" game setting, ranging from 1200 years at 5x habitable planets to 390 years at 0. 25x habitable planets. When a species becomes sapient this way, they will lose their presapient trait, but will usually gain some regular traits based on it, and will gain some random traits as well. If they were on a colony of a non-primitive empire, they will receive a citizenship type depending on the country's pre-sapients policy. If they shared a planet with an existing primitive civilization, they will become Serviles if they had the "Proles" or "Conservative" trait. If they are on an otherwise uninhabited planet, they will become a new stone aged primitive civilization with 0 tech progress. Emerging Subterraneans Occasionally a subterranean civilization will emerge. This happens at a rate scaling with the "Primitive Civilizations" game setting and with galaxy size. In a medium-sized galaxy with 1x primitives