Replaced the P-Buffer implementation of RenderImage with a generic "in-memory context" one

include/SFML/Graphics/RenderImage.hpp

@@ -177,20 +177,6 @@ public :
     ////////////////////////////////////////////////////////////
     const Image& GetImage() const;
 
-    ////////////////////////////////////////////////////////////
-    /// \brief Check whether the system supports render images or not
-    ///
-    /// It is very important to always call this function before
-    /// trying to use the RenderImage class, as the feature may not
-    /// be supported on all platforms (especially very old ones).
-    /// If this function returns false, then you won't be able
-    /// to use the class at all.
-    ///
-    /// \return True if the RenderImage class can be used
-    ///
-    ////////////////////////////////////////////////////////////
-    static bool IsAvailable();
-
 private :
 
     ////////////////////////////////////////////////////////////

include/SFML/Window/Context.hpp

@@ -30,6 +30,7 @@
 ////////////////////////////////////////////////////////////
 #include <SFML/Config.hpp>
 #include <SFML/Window/GlResource.hpp>
+#include <SFML/Window/ContextSettings.hpp>
 #include <SFML/System/NonCopyable.hpp>
 
 
@@ -69,8 +70,25 @@ public :
     ///
     /// \param active True to activate, false to deactivate
     ///
+    /// \return True on success, false on failure
+    ///
     ////////////////////////////////////////////////////////////
-    void SetActive(bool active);
+    bool SetActive(bool active);
+
+public :
+
+    ////////////////////////////////////////////////////////////
+    /// \brief Construct a in-memory context
+    ///
+    /// This constructor is for internal use, you don't need
+    /// to bother with it.
+    ///
+    /// \param settings Creation parameters
+    /// \param width    Back buffer width
+    /// \param height   Back buffer height
+    ///
+    ////////////////////////////////////////////////////////////
+    Context(const ContextSettings& settings, unsigned int width, unsigned int height);
 
 private :
 

include/SFML/Window/ContextSettings.hpp

@@ -45,7 +45,7 @@ struct ContextSettings
     /// \param minor        Minor number of the context version
     ///
     ////////////////////////////////////////////////////////////
-    explicit ContextSettings(unsigned int depth = 24, unsigned int stencil = 8, unsigned int antialiasing = 0, unsigned int major = 2, unsigned int minor = 0) :
+    explicit ContextSettings(unsigned int depth = 0, unsigned int stencil = 0, unsigned int antialiasing = 0, unsigned int major = 2, unsigned int minor = 0) :
     DepthBits        (depth),
     StencilBits      (stencil),
     AntialiasingLevel(antialiasing),