Ah, that, I guess, answers the licensing question for me.
And, now that I thought about it, String.split() method uses a REGEX for splitting the input string, meanwhile PApplet.split() uses just a normal string.
I guess it would make sense to keep their split() for backwards compatibility, and that replacing their code with something that converts that normal string to a REGEX compliant filter(I guess by adding a backslash before every character) would be slower.
Thanks!