Refactoring/adjustments

Various minor fixes/ reversions:

- no composer.lock
- adjusted travis.yml
- fixed utf8 issue in class comments
- re-enabled testsuite (using new binary)
- made standard name obligatory for binary selecting (using directory name by default)
- adjusted readme to suggest latest PHP only
- reverted phpcs version range

What is the reason for removing the composer.lock file? It is official recommended to save this in git (see https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file "Commit your application's composer.lock (along with composer.json) into version control.").