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/Services/Interfaces/ICoreService.cs

@@ -20,6 +20,11 @@ namespace Artemis.Core.Services.Interfaces
         /// </summary>
         bool ModuleRenderingDisabled { get; set; }
 
+        /// <summary>
+        ///     Initializes the core, only call once
+        /// </summary>
+        void Initialize();
+
         /// <summary>
         ///     Occurs the core has finished initializing
         /// </summary>