Rename `json::parser::write` to `read`

Naming `a::b` usually implies "a does b", e.g. `std::vector::push_back` means "vector pushes back". By definition, parser never writes, it only reads data so this method should be named `json::parser::read/consume/etc`.

`json::serializer::read` has the same problem, `obj.read(data, size)` means object reads data of given size, `serializer::read` actually *writes* some data into the given buffer. Don't know if there are other components with this problem.