rjson : a minimal json parser for rust

Contain a single standalone lib.rs that do all the jobs.
Impl the traits with your own structs before parse.
A simple Impl can be, enum for Value, the same enum for Null, Vec for Array and BTreeMap for Object.
It requires only core and alloc, nothing else, including std.
In no_std environment, it need a global allocator to work.

Reminder

We allow , after the last item/member of Array/Object.
We treat unescaped line breaks as normal char, and ignore escaped line breaks.
We do not support surrogate unicode char.
We use f64 for all numbers, but you can use others. Remind: f64 means i52.
We take &[char], not &[u8], and not &str.
No stringify or encode, because they should not be a part of the traits.
Instead of returning None, we simply ignore chars after the data.
The position where data ends is returned through index. You can compare it with len() - 1.
This value is also useful when Option::None returned, by indicating where the syntax error occurs.
parse may return all possible values, not only Array and Object.