support xml anonymity content

1. support Qt6

2. rapidjson remove std::string dependence

3. remove utf8-bom from files

4. support MySQL

Json data (#37)

* use shared ptr in json data

* add english readme

* Update README-en.md

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static assert if use pointer

Fix the bug that the string will be truncated when it contains u0000

fix some xml and bson bug (#2)

* add encoder wrapper and support bson

* fix atoi bug when val==0 and exception in xml decode when use M in case of empty string

* encoder object end add key

support xml (#1)

* support xml and fix clang warning
* support custom encode/decode
* update readme