Added struct methods to group builder

Bumped version number and also made only one app start in examples.

appveyor.yml

@@ -1,4 +1,4 @@
-version: 3.11.{build}
+version: 3.12.{build}
 branches:
   only:
   - master

src/EcsRx.Examples/Program.cs

@@ -42,7 +42,7 @@ static void Main(string[] args)
             //new Struct3Application().StartApplication();
             //new Class4Application().StartApplication();
             //new Struct4Application().StartApplication();            
-            new Struct4BApplication().StartApplication();
+            //new Struct4BApplication().StartApplication();
 
         }
     }

src/EcsRx/Groups/GroupBuilder.cs

@@ -35,7 +35,18 @@ public GroupBuilder WithoutComponent<T>() where T : class, IComponent
             _withoutComponents.Add(typeof(T));
             return this;
         }
-
+
+        public GroupBuilder WithStructComponent<T>() where T : struct, IComponent
+        {
+            _withComponents.Add(typeof(T));
+            return this;
+        }
+
+        public GroupBuilder WithoutStructComponent<T>() where T : struct, IComponent
+        {
+            _withoutComponents.Add(typeof(T));
+            return this;
+        }
 
         public GroupBuilder WithPredicate(Predicate<IEntity> predicate)
         {