Core - Added ways for the core to easily access brush properties

%*/@ me, dealing with generic types in APIs is tricky

src/Artemis.Core/Models/Profile/LayerProperties/BaseLayerProperty.cs

@@ -1,13 +1,46 @@
-using Artemis.Storage.Entities.Profile;
+using System;
+using System.Collections.Generic;
+using Artemis.Storage.Entities.Profile;
 
 namespace Artemis.Core.Models.Profile.LayerProperties
 {
+    /// <summary>
+    /// For internal use only, to implement your own layer property type, extend <see cref="LayerProperty{T}"/> instead.
+    /// </summary>
     public abstract class BaseLayerProperty
     {
         /// <summary>
         ///     Used to declare that this property doesn't belong to a plugin and should use the core plugin GUID
         /// </summary>
         internal bool IsCoreProperty { get; set; }
+        internal PropertyEntity PropertyEntity { get; set; }
+        internal LayerPropertyGroup LayerPropertyGroup { get; set; }
+
+        /// <summary>
+        ///     Gets whether keyframes are supported on this property
+        /// </summary>
+        public bool KeyframesSupported { get; protected set; }
+
+        /// <summary>
+        ///     Gets or sets whether keyframes are enabled on this property, has no effect if <see cref="KeyframesSupported" /> is
+        ///     False
+        /// </summary>
+        public bool KeyframesEnabled { get; set; }
+
+        /// <summary>
+        ///     Gets or sets whether the property is hidden in the UI
+        /// </summary>
+        public bool IsHidden { get; set; }
+
+        /// <summary>
+        ///     Indicates whether the BaseValue was loaded from storage, useful to check whether a default value must be applied
+        /// </summary>
+        public bool IsLoadedFromStorage { get; internal set; }
+
+        /// <summary>
+        ///     Gets the total progress on the timeline
+        /// </summary>
+        public TimeSpan TimelineProgress { get; internal set; }
 
         /// <summary>
         ///     Applies the provided property entity to the layer property by deserializing the JSON base value and keyframe values
@@ -21,5 +54,8 @@ namespace Artemis.Core.Models.Profile.LayerProperties
         ///     <see cref="ApplyToLayerProperty" />
         /// </summary>
         internal abstract void ApplyToEntity();
+
+        internal abstract List<TimeSpan> GetKeyframePositions();
+        internal abstract TimeSpan GetLastKeyframePosition();
     }
 }