Update the Unicode escape syntax

[perillo]

Update the old invalid legacy syntax to the new one.

[perillo]

See also the pending #80, where the same issue is fixed in 03d19a6.

[Techatrix]

According to the current Zig grammar, escape sequences like \u{0FFFFFF} are valid so this change isn't quite right. I fixed this issue in 0c10086

[perillo]

@Techatrix, thanks.

[perillo]

About the escape sequence, https://ziglang.org/documentation/master/#Escape-Sequences says that the unicode escape sequence is u{\x\{6}, while the current code is u{\x\+}.

[Techatrix]

This is what the language reference documents:

...	...
\xNN	hexadecimal 8-bit byte value (2 digits)
\u{NNNNNN}	hexadecimal Unicode scalar value UTF-8 encoded (1 or more digits)

It says 1 or more digits and not exactly six. The \u{NNNNNN} is just an example. The actual reference for how the Zig syntax looks like is the grammar in the language reference and on ziglang/zig-spec. See ziglang/zig#2823

[perillo]

@Techatrix, indeed, const string = "\u{FFFFFF}"; is a compiler error.

This means that the https://ziglang.org/documentation/master/#Escape-Sequences should be updated.

I also noted that the Zig Language reference uses code point while the Zig grammar uses char.

Thanks.