7.x
Update copyright year
Remove capacity from `JsonDocument`'s constructor
Rename `CollectionData.hpp` to `CollectionIterator.hpp`
Tests: add user-defined literal `""_s` for `std::string`
Fix integer overflow in MsgPackDeserializer
Don't store string literals by pointer anymore
Move some numbers tests to `use_double_0.cpp`
Store 64-bit numbers (`double` and `long long`) in an additional slot