Plugin settings window - Updated design

Brushes - Added option for brushes to have a settings window
Effects - Added option for effects to have a settings window

src/Artemis.Core/Plugins/Abstract/ViewModels/BrushConfigurationViewModel.cs

@@ -0,0 +1,15 @@
+using Artemis.Core.Plugins.LayerBrush.Abstract;
+using Stylet;
+
+namespace Artemis.Core.Plugins.Abstract.ViewModels
+{
+    public abstract class BrushConfigurationViewModel : Screen
+    {
+        protected BrushConfigurationViewModel(BaseLayerBrush layerBrush)
+        {
+            LayerBrush = layerBrush;
+        }
+
+        public BaseLayerBrush LayerBrush { get; }
+    }
+}

src/Artemis.Core/Plugins/Abstract/ViewModels/EffectConfigurationViewModel.cs

@@ -0,0 +1,15 @@
+using Artemis.Core.Plugins.LayerEffect.Abstract;
+using Stylet;
+
+namespace Artemis.Core.Plugins.Abstract.ViewModels
+{
+    public abstract class EffectConfigurationViewModel : Screen
+    {
+        protected EffectConfigurationViewModel(BaseLayerEffect layerEffect)
+        {
+            LayerEffect = layerEffect;
+        }
+
+        public BaseLayerEffect LayerEffect { get; }
+    }
+}

src/Artemis.Core/Plugins/Abstract/ViewModels/PluginConfigurationViewModel.cs

@@ -9,6 +9,6 @@ namespace Artemis.Core.Plugins.Abstract.ViewModels
             Plugin = plugin;
         }
 
-        public Plugin Plugin { get; set; }
+        public Plugin Plugin { get; }
     }
 }