Escape sequence for `?`

[dpb587]

go-patch introduces ? as a new, non-rfc6901 special character, but there's not an escape sequence defined. Preferences? Since non-standard, start in descending order; ~9?

https://github.com/cppforlife/go-patch/blob/37a72c69d59809d4d5aa0b2aff033e74b8014390/patch/pointer.go#L10-L11

[cppforlife]

@dpb587 dont have a pref. may be something high in the num range (99?)

[bgandon]

For completeness, I'd like to mention here this comment by Dmitriy that suggests the ~2 sequence for escaping ?.