Fix interpolated string rendering issues

[osyrisrblx]

Fixes #458 and #484

#458: Incorrect escaping for multi-line interpolated string literals

The issue was that the escape logic did not pick up Windows-style line endings properly. For this we need to also check for \r followed by an optional \n.

Input

warn(`look I am
a multiline string`)

Before

warn(`look I am
\
a multiline string`)

After

warn(`look I am\
a multiline string`)

#484: Incorrect escaping for unicode escape sequences in interpolated string literals

Input

const string_a = "\u{E000}";
const string_b = `\u{E000}`;

Before

local string_a = "\u{E000}"
local string_b = `\u\{E000\}`

After

local string_a = "\u{E000}"
local string_b = `\u{E000}`

[Dionysusnu]

This regex might be cleaner with a negative lookbehind instead of capturing the Unicode sequences to like-for-like replace them. Was it a conscious decision not to use one?

[osyrisrblx]

I wasn't able to find a way to do this that was readable. Open to suggestions.