Improve terminology

[medikoo]

Currently interfaces which are responsible for displaying logs are called writers, which can be confusing, as in similar way we may think of as a writer of interface through which logs are written (to the registry).

In popular loggers what's called writers is called transports or reporters. At this point I'm leaning towards reporter term (altough it's not just about writing but also about transformations to logs, and it's what transports do)

Such change will need to be followed with rename of *-writer modules, hence it'll be breaking