Add `--deprecation-out` CLI option.
Update the "too many deprecations" message.

...so that it mentions the new `--deprecation-out` CLI option.
Warn if setting `config.deprecation_stream` is ignored.
Merge pull request #1458 from rspec/deprecation-stream-fixes-3-0

Deprecation stream fixes 3 0
Rework color_enabled
remove backtrace_cleaner
remove filename_pattern as an alias of pattern (choosen because pattern matches cli)