User defined logging sets and presets

[binduwavell]

It would be awesome to provide a list of presets for all loggers. Say user wants to debug CMIS or Kerberos. It would be amazing to selec from a list of presets and quickly know the right loggers are enabled for the task at hand.

Additionally users may develop their own logging profiles/sets and wish to easily switch between them.

[AFaust]

Since we already maintain a model of logging level changes in the background it would come in handy for applying logging presets and subsequently being able to reset them again to the previous state.

Support of logging sets / presets will need to involve:

• exporting an efficient model of all current logging level settings, which should only contain the logger names and levels for actual level differences between parent/child logger (no point in including inherited levels)
• importing / activating the model and storing a kind of "restore marker" for the state immediately prior to the import / preset activation
• contextually replacing the "reset" button with a "disable preset" action to restore the logging configuration to the state prior to preset activation
• a lookup path for pre-defined presets on the classpath and a basic i18n property pattern for providing localised labels

Ideally we should use the Log4J properties configuration file format for defining presets so that users can define presets even without using our Log4J Settings tool and may include presets in their regular Log4J configuration files via the extension directory. Unfortunately Share does not support custom Log4J properties files out-of-the-box, so using the properties file format has less use here (unless a 3rd-party addon is used that provides for configurable Log4J settings in Share)