MAINT: update logging framew., add README_LOGGING.md

.gitignore

README_LOGGING.md

conf/core/log4j2-debug.properties

conf/core/log4j2-default.properties

conf/core/logging.conf

pom.xml

src/main/java/caosdb/server/CaosAuthenticator.java

src/main/java/caosdb/server/CaosDBServer.java

...java/caosdb/server/accessControl/AuthenticationUtils.java

src/main/java/caosdb/server/accessControl/Pam.java

src/main/java/caosdb/server/accessControl/UserSources.java

.../backend/implementation/MySQL/DatabaseConnectionPool.java

src/main/java/caosdb/server/datatype/GenericValue.java

src/main/java/caosdb/server/jobs/extension/AWIBoxLoan.java

...ain/java/caosdb/server/logging/BackendLoggingHandler.java

...in/java/caosdb/server/logging/RequestErrorLogMessage.java

...osdb/server/logging/log4j/CustomConfigurationFactory.java

src/test/java/caosdb/datetime/DateTimeTest.java

src/test/java/caosdb/server/database/InsertTest.java

src/test/java/caosdb/server/logging/TestLogging.java