Merge branch '3-improve-skins' into 'master'

Resolve "Improve skins"

Closes #3

See merge request !3

icons/skins/retro/6.svg

+<?xml version="1.0" encoding="UTF-8"?>
+<svg enable-background="new 0 0 100 100" version="1.1" viewBox="0 0 100 100" xml:space="preserve" xmlns="http://www.w3.org/2000/svg"><rect width="100" height="100" ry="2" fill="none"/><rect width="100" height="100" fill="#008834" stroke="#505050" stroke-linecap="round" stroke-linejoin="round" stroke-width="2.6"/></svg>

icons/skins/retro/7.svg

+<?xml version="1.0" encoding="UTF-8"?>
+<svg enable-background="new 0 0 100 100" version="1.1" viewBox="0 0 100 100" xml:space="preserve" xmlns="http://www.w3.org/2000/svg"><rect width="100" height="100" ry="2" fill="none"/><rect width="100" height="100" fill="#CC5200" stroke="#505050" stroke-linecap="round" stroke-linejoin="round" stroke-width="2.6"/></svg>

icons/skins/retro/8.svg

+<?xml version="1.0" encoding="UTF-8"?>
+<svg enable-background="new 0 0 100 100" version="1.1" viewBox="0 0 100 100" xml:space="preserve" xmlns="http://www.w3.org/2000/svg"><rect width="100" height="100" ry="2" fill="none"/><rect width="100" height="100" fill="#f0f" stroke="#505050" stroke-linecap="round" stroke-linejoin="round" stroke-width="2.6"/></svg>

icons/skins/symbols/0.svg

+<?xml version="1.0" encoding="UTF-8"?>
+<svg enable-background="new 0 0 100 100" version="1.1" viewBox="0 0 100 100" xml:space="preserve" xmlns="http://www.w3.org/2000/svg"><rect width="100" height="100" ry="2" fill="none"/><rect width="100" height="100" fill="#fff" stroke="#505050" stroke-linecap="round" stroke-linejoin="round" stroke-width="2.6"/></svg>

icons/skins/symbols/8.svg

+<?xml version="1.0" encoding="UTF-8"?>
+<svg enable-background="new 0 0 100 100" version="1.1" viewBox="0 0 100 100" xml:space="preserve" xmlns="http://www.w3.org/2000/svg"><rect width="100" height="100" ry="2" fill="none"/><rect width="100" height="100" fill="#c5c5c5" stroke="#505050" stroke-linecap="round" stroke-linejoin="round" stroke-width="2.6"/><path transform="rotate(-4.8261 273.96 -149.1)" d="m52.681 60.363c-1.9927 1.1506-17.752-11.111-20.045-11.3-2.2178-0.18265-19.136 9.4253-20.79 7.9363-1.7101-1.5396 5.0812-20.316 4.5522-22.556-0.51164-2.1657-14.877-15.287-13.972-17.32 0.93585-2.1022 20.892-1.4456 22.859-2.6408 1.9016-1.1558 9.9417-18.873 12.155-18.641 2.2885 0.24044 7.8309 19.423 9.5752 20.924 1.6869 1.4514 21.022 3.6229 21.485 5.7996 0.4785 2.2508-16.052 13.45-16.941 15.572-0.85907 2.0529 3.0505 21.112 1.1233 22.225z" fill="none" stroke="#121212" stroke-linecap="round" stroke-linejoin="round" stroke-width="14"/></svg>

lib/provider/data.dart

@@ -4,15 +4,15 @@ import 'package:shared_preferences/shared_preferences.dart';
 class Data extends ChangeNotifier {
 
   // Configuration available values
-  List _availableLevelValues = ['easy', 'normal', 'hard', 'nightmare'];
-  List _availableSkinValues = ['default', 'images'];
+  List _availableLevelValues = ['easy', 'medium', 'hard', 'nightmare'];
+  List _availableSkinValues = ['default', 'retro', 'symbols'];
 
   List get availableLevelValues => _availableLevelValues;
   List get availableSkinValues => _availableSkinValues;
 
   // Application default configuration
   String _level = '';
-  String _levelDefault = 'normal';
+  String _levelDefault = 'medium';
   String _skin = '';
   String _skinDefault = 'default';