Logging guide

• The project uses the java.util.logging package for logging.
• LogsCenter manages logging levels and destinations.
• A class obtains a Logger with LogsCenter.getLogger(Class), which logs messages at the configured level.
• Log messages are written to the console and a .log file.
• The output logging level can be controlled by changing the LOG_LEVEL constant in the LogsCenter class.
• When choosing a level for a log message, follow the conventions given in [se-edu/guides] Java: Logging conventions.