I created a faster JSON parser

[Herman , Géza]

Hi,

I created a faster JSON parser for emacs, you can check it out 
here:

https://github.com/geza-herman/emacs/tree/faster-json-parsing

It replaces json-parse-string and json-parse-buffer functions. 
The behavior should be the same as before, with the only exception 
that objects with duplicated keys are not detected if :object-type 
is not 'hash-table.

This parser runs 8-9x faster than the jansson based parser on my 
machine (tested on clangd language server messages).  An 
additional tiny benefit is that large integers are parsed, instead 
of having an "out of range" error.

What do you think?

Geza