Make BlockRepresentation a builder-style

[democat3457]

Fixes #237

Although the issue isn't really a bug, I can see the use in having a chain-style return to allow for more efficient code. (So this is more of a feature suggestion)

I would imagine the other Representations would have to be matched for parity between them?

[SkySom]

Sure I totally agree that builder style is nicer. Which is why 1.16 uses it. At this point all 1.12 docs uses normal setters and honestly I'm not willing to risk what changing the type could do at this point.

[democat3457]

/shrug

It's not like this would affect backwards-compatibility though, since changing a type from void to BlockRepresentation wouldn't affect existing scripts. (It would direct the returned value to nothing, but it would still alter the variable used.)