Condition operators - Marked built-in operators as internal

Display conditions - Added docs to the service and profile types
Color gradient - Added docs
Storage - Moved profile entities to separate namespaces
Data bindings - Added entities to storage
Data bindings - Started implementing in the core

src/Artemis.Core/Models/Profile/DataBindings/DataBinding.cs

@@ -0,0 +1,60 @@
+using System.Collections.Generic;
+using Artemis.Core.Models.Profile.LayerProperties;
+using Artemis.Core.Plugins.DataModelExpansions;
+
+namespace Artemis.Core.Models.Profile.DataBindings
+{
+    /// <summary>
+    ///     A data binding that binds a certain <see cref="BaseLayerProperty" /> to a value inside a <see cref="DataModel" />
+    /// </summary>
+    public class DataBinding
+    {
+        private readonly List<DataBindingModifier> _modifiers = new List<DataBindingModifier>();
+
+        /// <summary>
+        ///     The <see cref="BaseLayerProperty" /> that the data binding targets
+        /// </summary>
+        public BaseLayerProperty Target { get; set; } // BIG FAT TODO: Take into account X and Y of SkPosition etc., forgot about it again :>
+
+        /// <summary>
+        ///     Gets the currently used instance of the data model that contains the source of the data binding
+        /// </summary>
+        public DataModel SourceDataModel { get; private set; }
+
+        /// <summary>
+        ///     Gets the path of the source property in the <see cref="SourceDataModel" />
+        /// </summary>
+        public string SourcePropertyPath { get; private set; }
+
+        /// <summary>
+        ///     Gets a list of modifiers applied to this data binding
+        /// </summary>
+        public IReadOnlyList<DataBindingModifier> Modifiers => _modifiers.AsReadOnly();
+
+        /// <summary>
+        ///     Adds a modifier to the data binding's <see cref="Modifiers" /> collection
+        /// </summary>
+        public void AddModifier(DataBindingModifier modifier)
+        {
+            if (!_modifiers.Contains(modifier))
+            {
+                modifier.DataBinding = this;
+                modifier.CreateExpression();
+                _modifiers.Add(modifier);
+            }
+        }
+
+        /// <summary>
+        ///     Removes a modifier from the data binding's <see cref="Modifiers" /> collection
+        /// </summary>
+        public void RemoveModifier(DataBindingModifier modifier)
+        {
+            if (_modifiers.Contains(modifier))
+            {
+                modifier.DataBinding = null;
+                modifier.CreateExpression();
+                _modifiers.Remove(modifier);
+            }
+        }
+    }
+}