FS#25 - Change sf::PostFx to a more general purpose pixel shader class (sf::Shader)

Updated the PostFx sample, renamed to Shader
Renamed all the static X::CanUseX() functions to X::IsAvailable() to make the API more consistent
Moved .def files from /build/VC200X to /src in CSFML
Minors fixes in CSFML

git-svn-id: https://sfml.svn.sourceforge.net/svnroot/sfml/branches/sfml2@1258 4e206d99-4929-0410-ac5d-dfc041789085

samples/voip/Client.cpp

@@ -63,7 +63,7 @@ private :
 void DoClient(unsigned short port)
 {
     // Check that the device can capture audio
-    if (sf::SoundRecorder::CanCapture() == false)
+    if (sf::SoundRecorder::IsAvailable() == false)
     {
         std::cout << "Sorry, audio capture is not supported by your system" << std::endl;
         return;