Accept Emitter::operator<<(std::string_view).
ABI remains C++11 compatible by exposing new method
Emitter::Write(const char*, size_t).
All affected calls optimized to pass std::string values as pointer + size
tuple into appropriate routines.
For completeness I've implemented escaping for characters outside the
basic multilingual plane, but it doesn't get used (as there's no
EscapeAsAsciiJson emitter option implemented).
Inside of a sequence or map, `YAML::Newline` wouldn't reset the collection state, which would cause behavior like this:
```
nodeA:
k: [{i: 0},
{i:1},
]NodeB:
k: [{i: 0},
{i:1},
]
```
The issue is that numbers like
2.01 or 3.01 can not be precisely represented with binary floating point
numbers.
This replaces all occurrences of 'std::numeric_limits<T>::digits10 + 1' with
'std::numeric_limits<T>::max_digits10'.
Background:
Using 'std::numeric_limits<T>::digits10 + 1' is not precise enough.
Converting a 'float' into a 'string' and back to a 'float' will not always
produce the original 'float' value. To guarantee that the 'string'
representation has sufficient precision the value
'std::numeric_limits<T>::max_digits10' has to be used.