- use new way to manage iconv token, instead of std::unique_ptr which cause template error (no viable sizeof) in pycodec.
- fix the wrong name in pycodec.
- remove useless code.
- add endian and compiler detector, and modify os detector.
- now we use CMake to add detector-used macro, instead of using some C++ features to detect them.
- change Windows environment detection according to the change of os detector.
