Rename DebugFilter to DevelopmentFilter

The name `DebugFilter` often caused confusing where users thought it would
actually display all log messages. While Flutter uses the term 'debug' build
this is not used in the wider Dart community. Especially when talking about a
logs the name 'debug' is overloaded with the old class name. The new name
reflects clearly when you should be using this filter.

Author: haarts

README.md

@@ -102,7 +102,7 @@ import `io`, for example when using this library on the web.
 ## LogFilter
 
 The `LogFilter` decides which log events should be shown and which don't.<br>
-The default implementation (`DebugFilter`) shows all logs with `level >= Logger.level` while in debug mode. In release mode all logs are omitted.
+The default implementation (`DevelopmentFilter`) shows all logs with `level >= Logger.level` while in debug mode. In release mode all logs are omitted.
 
 You can create your own `LogFilter` like this:
 ```dart

lib/src/filters/debug_filter.dart

@@ -1,11 +1,11 @@
 import 'package:logger/src/logger.dart';
 import 'package:logger/src/log_filter.dart';
 
-/// Default implementation of [LogFilter].
+/// Prints all logs with `level >= Logger.level` while in development mode (eg
+/// when `assert`s are evaluated, Flutter calls this debug mode).
 ///
-/// Prints all logs with `level >= Logger.level` while in debug mode. In release
-/// mode all logs are omitted.
-class DebugFilter extends LogFilter {
+/// In release mode ALL logs are omitted.
+class DevelopmentFilter extends LogFilter {
   @override
   bool shouldLog(LogEvent event) {
     var shouldLog = false;

lib/src/log_filter.dart

@@ -2,7 +2,7 @@ import 'package:logger/src/logger.dart';
 
 /// An abstract filter of log messages.
 ///
-/// You can implement your own `LogFilter` or use [DebugFilter].
+/// You can implement your own `LogFilter` or use [DevelopmentFilter].
 /// Every implementation should consider [Logger.level].
 abstract class LogFilter {
   Level level;

lib/src/logger.dart

@@ -54,14 +54,14 @@ class Logger {
   /// Create a new instance of Logger.
   ///
   /// You can provide a custom [printer], [filter] and [output]. Otherwise the
-  /// defaults: [PrettyPrinter], [DebugFilter] and [ConsoleOutput] will be
+  /// defaults: [PrettyPrinter], [DevelopmentFilter] and [ConsoleOutput] will be
   /// used.
   Logger({
     LogFilter filter,
     LogPrinter printer,
     LogOutput output,
     Level level,
-  })  : _filter = filter ?? DebugFilter(),
+  })  : _filter = filter ?? DevelopmentFilter(),
         _printer = printer ?? PrettyPrinter(),
         _output = output ?? ConsoleOutput() {
     _filter.init();