fix: unify the loggers

[c-dilks]

⚠️ Breaking Changes ⚠️

• changed OptionParser default log level from FINE to INFO; this means logs will be quieter by default
• classes which called DefaultLogger.debug(), which effectively sets the log level to FINE, will also be quieter

🐛 Bug Fix 🐛

• remove DefaultLogger, fixing Stderr and stdout are being hijacked #947, since using DefaultLogger and SplitLogger simultaneously causes neither of them to work at all
• the "standard" logger instances (via Logger.getLogger and similar) remain for now
  • PR fix: use SplitLogger for all loggers #952 is a followup PR that proposes converting them to SplitLogger
  • if any such stream "hijacking" continues to occur, using SplitLogger everywhere "should" fix things once and for all

🚧 Features 🚧

• propagate log level of OptionParser (which user sets with -l) to all new SplitLogger instances
  • handled by new singleton SplitLoggerConfig
  • parser.syncLogLevel() may be used to set the level of a Logger to match this level; typically used when an OptionParser instance owner also owns a Logger instance
  • parser.overrideLogLevel() may be used to override the level of a SplitLogger for any class, to handle the case where we don't want the level of OptionParser or SplitLoggerConfig to be used