Prevent replacement of {\d+} sequences in chat.format and remove stray '

[zford]

This fixes issues presented by khobbits with the latest chat.format brace fix.

https://github.com/phrstbrn/Essentials/commit/8fde5102b9161cda2267d3638c15dc6fda48a7fd#commitcomment-2494321

Unfortunately the regex to fix it is gross (and largely unreadable), however, it does fix the issue and a few other edge cases.

[khobbits]

I'm not sure this can be considered an improvement :s

[zford]

Oh come on, everybody knows what (?:^|(?<=[^\d'])|(?<=\d'}'))([{}][{}']*)(?:$|(?=[^\d'])|(?='{'\d)) does!

In all seriousness, it does fix the actual problem presented with that commit. I couldn't figure out a cleaner way of doing it without that nasty regex.

[khobbits]

This feels more like a hack than a fix, i'd rather not have such a horrible regex in there, for readability, maintainability and performance reasons.