I initially tried to use the existing .clang-format file,
but it does not match the code style (at least with clang-format 11)
and the formatting is not consistent across files.
Therefore, I decided to rewrite the .clang-format with some personal
preferences.
Used command
find . -iname "*.hpp" -o -iname "*.cpp" | xargs clang-format -i -style=file
- fix issue #399.
- make to_json() with an empty Map, Vector or Dynamic_Object return a
similar/compatible type (JSON object or array), rather than "null".
- include the fix for #381 (to_json() support for null values), so
that can also be unit tested.
