Added Circle

Build/Projects/MonoGame.Framework.definition

@@ -183,6 +183,7 @@
     <Compile Include="BoundingBox.cs" />
     <Compile Include="BoundingFrustum.cs" />
     <Compile Include="BoundingSphere.cs" />
+    <Compile Include="Circle.cs" />
     <Compile Include="Color.cs" />
     <Compile Include="ContainmentType.cs" />
     <Compile Include="CurveContinuity.cs" />
@@ -332,6 +333,7 @@
     <Compile Include="Content\ContentReaders\BoundingSphereReader.cs" />
     <Compile Include="Content\ContentReaders\ByteReader.cs" />
     <Compile Include="Content\ContentReaders\CharReader.cs" />
+    <Compile Include="Content\ContentReaders\CircleReader.cs" />
     <Compile Include="Content\ContentReaders\ColorReader.cs" />
     <Compile Include="Content\ContentReaders\CurveReader.cs" />
     <Compile Include="Content\ContentReaders\DateTimeReader.cs" />

Build/Projects/MonoGame.Tests.definition

@@ -85,6 +85,7 @@
     </Compile>
 
     <Compile Include="Framework\Bounding.cs" />
+	<Compile Include="Framework\CircleTest.cs" />
     <Compile Include="Framework\ColorTest.cs" />
 	<Compile Include="Framework\CurveKeyCollectionTest.cs" />
 	<Compile Include="Framework\CurveKeyTest.cs" />

Documentation/improvements.md

@@ -1,12 +1,13 @@
 The new API features which are available in the current development release and does not exist in XNA.
 
+
 ##Graphics and window routines
 
 [GameWindow.AllowAltF4](http://www.monogame.net/documentation/?page=P_Microsoft_Xna_Framework_GameWindow_AllowAltF4) - boolean that allows or disallow using Alt+F4 combo for game window closing. You can change it anytime in your code. Note : this isnt working on WinRT projects because Alt+F4 is intended to work always on this platform.
 
 [GameWindow.IsBorderless](http://www.monogame.net/documentation/?page=P_Microsoft_Xna_Framework_GameWindow_IsBorderless) - boolean that makes border of your window invisible. You cannot move or resize your game window after this boolean setted to true. Works only on desktop platforms.
 
-##Math
+##Math and geometry routines
 
 [MathHelper.Clamp(int,int,int)](http://www.monogame.net/documentation/?page=M_Microsoft_Xna_Framework_MathHelper_Clamp_1) - this overload clamps integers instead floats which could be useful in some cases. You dont need to convert like this MathHelper.Clamp((float)integer,(float)min,(float)max) anymore.
 
@@ -34,6 +35,23 @@ Vector2 vector2 = new Vector2(10.01f,10.99f);
 var point = vector2.ToPoint(); // point will be 10,10.
 ```
 
+[Circle](http://www.monogame.net/documentation/?page=T_Microsoft_Xna_Framework_Circle) - A Circle which can be used for circle-based bounds and collisions. Circle contains methods of getting points on the circles edge with a specified radii in addition to ones for checking intersection with other Circles and [Rectangles](http://www.monogame.net/documentation/?page=T_Microsoft_Xna_Framework_Rectangle)
+
+```
+
+	Circle circle = new Circle(new Vector2(200.0f, 300.0f), 100.0f);
+	Rectangle rectangleAroundCircle = circle.ToRectangle();
+
+	bool containsFloat = circle.Contains(200.0f, 300.0f);
+	bool containsPoint = circle.Contains(new Point(200, 300));
+	bool containsVector2 = circle.Contains(new Vector2(200.0f, 300.0f));
+	bool containsCircle = circle.Contains(new Circle(new Vector2(200.0f, 300.0f), 25.0f));
+
+	bool intersectsCircle = circle.Intersects(new Circle(new Vector2(350.0f, 300.0f), 100.0f));
+	bool intersectsRectangle = circle.Intersects(new Rectangle(250, 350, 150, 100));
+
+```
+
 ##Input
 
 [MouseState.Position](http://www.monogame.net/documentation/?page=P_Microsoft_Xna_Framework_Input_MouseState_Position) - property which returns a [Point](http://www.monogame.net/documentation/?page=T_Microsoft_Xna_Framework_Point) which contains X and Y parameters of MouseState. Before this change it is harder to obtain mouse position in a good way. You can now write something like this