Adapt logger to be more dartly

[wrozwad]

I think that this library should me more Dart like in place of Android like. So for me there will be better to use Dart Levels (package:logging/logging.dart) in place of android levels.

I made some mapping from Android to dart logging levels:

library Levels	Native Levels
nothing	ALL
---	FINEST
---	FINER
verbose	FINE
debug	CONFIG
info	INFO
warning	WARNING
error	SEVERE
wtf	SHOUT

And I implemented it in custom LogOutput:

import 'dart:developer';

import 'package:logger/logger.dart';
import 'package:logging/logging.dart' as dartLog;

class PrettierConsoleOutput extends LogOutput {
  final _lvlMapping = {
    Level.nothing: dartLog.Level.ALL.value,
    Level.verbose: dartLog.Level.FINE.value,
    Level.debug: dartLog.Level.CONFIG.value,
    Level.info: dartLog.Level.INFO.value,
    Level.warning: dartLog.Level.WARNING.value,
    Level.error: dartLog.Level.SEVERE.value,
    Level.wtf: dartLog.Level.SHOUT.value,
  };

  @override
  void output(OutputEvent event) {
    for (var line in event.lines) {
      log(line, level: _lvlMapping[event.level]);
    }
  }
}

It gives us much better log filtering and you can easly add colors to them:
flutter/flutter-intellij#2200 (comment)

[haarts]

I like that the IDEs (Android Studio too) has support for this. Especially since colouring of console output in the IDEs doesn't work. This goes on my todo list.

[KlausJokisuo]

@sosite I'm unable to produce coloring on Android Studio output.

      dartLog.Level.LEVELS.forEach((level) {
        developer.log('Test!', level: level.value);
      });

Any tips?