Add option to use clew to manually open the OpenCL dynamic library

fix Linux build of App_Bullet3_OpenCL_Demos. Unfortunately the simulation doesn't work properly, need to fix it
(and add unit tests)

test/clew/premake4.lua

@@ -0,0 +1,27 @@
+
+
+project ("Test_clew")
+
+	language "C++"
+			
+	kind "ConsoleApp"
+	targetdir "../../bin"
+	includedirs {"../../src/clew"}
+	
+	if os.is("Windows") then 
+		defines { "WIN32" }
+		links {"Ws2_32","Winmm"}
+	end
+	if os.is("Linux") then
+		links {"dl"}
+	end
+	if os.is("MacOSX") then
+	end		
+		
+	
+	files {
+		"clewTest.cpp",
+		"../../src/clew/clew.c",
+		"../../src/clew/clew.h"
+	}
+