[server] Logging - logback

[black-snow]

The server prints to stdout and stderr although we have slf4j/logback at hand.

I fixed this by:

• adding a private static final Logger LOG = LoggerFactory.getLogger(ServerTools.class);
• replacing org.languagetool.server.ServerTools::print with appropriate calls to the Logger
• adding date and log-level to the log-pattern

I also had to delete languagetool-server/src/main/resources/logback.xml, otherwise my provided logback config -Dlogback.configurationFile=logback.xml would not be used.

I'll file a PR if you're interested.

In the long run we should probably also consider using the log levels properly. I modified the ServerTool's print() to use info/error depending on wether PrintStream is System.err or not but we can do better.

/edit: This seems related.

[danielnaber]

I'll file a PR if you're interested.

Yes, please do.

[black-snow]

https://github.com/languagetool-org/languagetool/pull/2128