Add ### multi-line comment support.

[Moderocky]

Description

This adds support for multi-line comments, originally requested here.

We agreed on very strict specifications: Multi-line comments can't start or end part-way through a line (for clarity).
(So you can't do on script ### comment ### load:!)

A block comment is opened and closed with three hashtag characters ###.

###
This is a comment!!!
###

this is no longer a comment

This (###) must be the only thing on the line. This was to try and avoid breaking any existing weird comment set-ups in scripts (although multi-hashtag ### comments have only been permitted since December 2023 anyway!)

This means that three hashtags followed by some text won't start (or end) a multi-line comment.

# This is a regular comment
### This is also a regular comment
########## This is still a regular comment

###

This is a comment!!!
### this is also inside the comment

###

An error is thrown if a script opens a multi-line comment and never closes it.

---

Target Minecraft Versions: any
Requirements: none
Related Issues: closes 2180

[7othifaPS]

but what if some minehut users put like this

###
###
this is string

Will this is string be code or comment

[sovdeeth]

but what if some minehut users put like this

###
###
this is string

Will this is string be code or comment

Code. You started a block and ended a block, so now you're back to code space.

[AyhamAl-Ali]

Nice work Kenzie ⚡

[EquipableMC]

Will this affect if it's being used in actual code?

[sovdeeth]

Will this affect if it's being used in actual code?

Please see the PR description:

We agreed on very strict specifications: Multi-line comments can't start or end part-way through a line (for clarity).
(So you can't do on script ### comment ### load:!)

This (###) must be the only thing on the line.

[EquipableMC]

Oh I didn't see that sorry