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?

go-patch/patch/pointer.go

Lines 10 to 11 in 37a72c6

	rfc6901Decoder = strings.NewReplacer("~0", "~", "~1", "/")
	rfc6901Encoder = strings.NewReplacer("~", "~0", "/", "~1")

[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 ?.