Clarify the concept of "collective mind state"

Preparing #11

Instead of the concepts of individual vs. collective mind states, we should probably use the terms:
- *Subjective experience*, because it is a usual concept in the scientific literature in the domain of philosophy of mind and because its meaning is intuitively clear for non-specialists, too. This term focuses on the individual character ("subjective") and on the contents ("experience") rather than on its support ("mental entity", "soul", etc.)
- *Mental state*, because it doesn't suggest the existence of an entity ("collective mind") which could support "paranormal" theories, and because it draws a parallel to the *quantum state* of the universe and focuses thus on the simultaneous character ("state") of the subjective experiences taking place in the universe rather than on their support ("God", "mental entities", "souls", "universal mind", etc.)

@rlpvimal I guess this would probably make things much easier to understand, what do you think? I don't want to elaborate any theory about the support of subjective experience in my book, because this would be highly speculative metaphysics. Of course, this would be interesting, but I don't want to focus on a single metaphysics, I'd rather like to define a general naturalistic framework in which different metaphysics could be embedded.