Use logger instead echo

Better to logger instead echo.
For example you can use use [this one](https://github.com/mougrim/php-logger) or monolog, or something else.
If you do not mind, I can create pull request with using [https://github.com/mougrim/php-logger](https://github.com/mougrim/php-logger).

No files, tests, or entry points are named. Start by locating the existing echo calls and reviewing how output is currently handled; clarify the logger choice and scope before changing anything, then verify that the agreed logging behavior replaces the relevant direct output.

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