Additional unittest for config.get method
OutputManager is replaced by GlobalLogger.

* Old staff is marked with 'deprecated'
* There is two phases: before loading a config (default config is used)
and after config is loaded (logger could change logging file)
* There is feature to setup verbosity levels both for outputing to
console and outputing to file
* Configuration is loaded in error-proof manner. All values are set to
default if config cannot find them
* Fully qualified logging section in config:
Game:
    Verbosity: !Verbosity High # OutputManager 
Logging: # GlobalLogger options
    FilePath: "dash.log" # Phase 2 logname
    Debug: # Is taken in debug build
        OutputVerbosity: !Verbosity High
        LoggingVerbosity: !Verbosity High
    Release: # Is taken in release build
        OutputVerbosity: !Verbosity High
        LoggingVerbosity: !Verbosity High