[CLOSED PR] New antagonist : Brain slugs

[Bartimeus]

Since i was waiting for information on what wraith needed the most, i went ahead and finished the PR.
Sprites and sounds are now in and that should be what was needed to take the PR off draft status.
I am not expecting a review soon, considering that wraith probably still has some glaring issues, but at least it's ready for review!
Thanks everyone for the valuable input!