Core - Added ColorGradient type to use for.. gradients!

Core - Initialisation process no longer takes place in core constructor and is no longer async
UI - Fixed exceptions during init not being shown
Gradient editor - Started work on this

src/Artemis.Core/Models/Profile/ColorGradient.cs

@@ -0,0 +1,28 @@
+using System.Collections.Generic;
+using SkiaSharp;
+
+namespace Artemis.Core.Models.Profile
+{
+    public class ColorGradient
+    {
+        public ColorGradient()
+        {
+            Colors = new List<ColorGradientColor>();
+        }
+
+        public List<ColorGradientColor> Colors { get; }
+        public float Rotation { get; set; }
+    }
+
+    public struct ColorGradientColor
+    {
+        public ColorGradientColor(SKColor color, float position)
+        {
+            Color = color;
+            Position = position;
+        }
+
+        public SKColor Color { get; set; }
+        public float Position { get; set; }
+    }
+}