The Position gives a means to index into the Tokenizer's underlying byte slice.
This enables use cases where the caller is planning on making edits to the JSON
document but wants to leverage the copy func to optimize data movement and/or 
to copy remaining bytes if the caller wants to exit the tokenizing loop early.

* fix encoding RawMessage that contains leading space.

* add json/bugs/issue136

* json: stylistic improvements, better code reuse

Initial benchmark results show this change
to be approximately performance-neutral.

* bump tested Go versions to just 1.20 and 1.21
* json: add ParseFlags values UseInt64, UseUint64, UseBigInt
* json: use atomic.Pointer

* allow rewrite rule overrides and add bitwise-or rewriter

* finish docs

* remove repeated, these apply a little odd in the rewriter

* go.mod: upgrade to 1.23 (oldest supported by Go project)

* json: encode `\b` and `\f` like the Go 1.22 stdlib does

https://go-review.googlesource.com/c/go/+/521675

* perf(json): revert decodeInto helper changes for object/array/string

* per(json): add benchmarks for decoding object and array with mixed members

* json: use reflect.PointerTo (avoid deprecated naming)
* json: use maps.Copy
* lint: remove unused consts/fields
* exclude stdlib copied tests from linting
* json: partial lint fixes