Overhaul of the introduction sequence

[wordandahalf]

(Addresses #9 and #10) As promised, here is the PR.

I would prefer if we could discuss the details here, so we can keep all of our ideas in one place 😄 I'm still in the process of commenting and renaming methods, but it seems like the current system is simple enough to work with going forward. For now, I'm going to disable all of the scenes except the one(s) we have an idea for (I am of course assuming that we are going to figure out new scenes rather than just replace Pikachu with Clefairy).

Current scene list:	Original scene	Friendly name	New scene
YellowIntroScene12	Pikachu close up	Clefairy close up
YellowIntroScene14	Pikachu thunderbolt	Clefairy metronome

[wordandahalf]

(Posting this for posterity)

It doesn't matter either way, but for now I plan on splitting the excellent animation Darkshade made into two separate parts (as described in the table above). An example GIF can be found here. Raw animation data can be found here. Tiles can be found here.

[wordandahalf]

Going to work on the disclaimer next.

[wordandahalf]

In Discord we discussed modifying the endgame credits. I'll do that, but in a different PR--credits are outside the scope of this one.