Add --deprecation-out CLI option.
Improve message a bit.
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 #1452 from rspec/deprecation-stream-fixes-2-99

Deprecation stream fixes 2 99
Deprecate config options
* deprecate color_enabled
* deprecate filename_pattern
* deprecate backtrace_cleaner