move OpenCL initialization for the unit tests in a shared header file, and support some basic command-line arguments

--cl_device=1 --cl_platform=1 --allow_opencl_cpu
add chaindemo, test for mass ratios
restore sleeping/activation mode in featherstone demo
Use _VARIADIC_MAX=10 to avoid Google Test issues with Visual Studio 2012, thanks to Mobeen for the report
Enable verbose printf for unit tests

test/TestBullet3OpenCL/main.cpp

@@ -9,7 +9,7 @@ void myerrorprintf(const char* msg)
 	printf(msg);
 }
 	
-static bool sVerboseWarning = false;
+static bool sVerboseWarning = true;
 
 void mywarningprintf(const char* msg)
 {
@@ -20,7 +20,7 @@ void mywarningprintf(const char* msg)
 	}
 }
 
-static bool sVerbosePrintf=false;
+static bool sVerbosePrintf=true;//false;
 
 void myprintf(const char* msg)
 {

test/TestBullet3OpenCL/premake4.lua

@@ -6,6 +6,12 @@ function createProject(vendor)
 	
 --	defines {  }
 	
+	if os.is("Windows") then
+		--see http://stackoverflow.com/questions/12558327/google-test-in-visual-studio-2012
+		defines {"_VARIADIC_MAX=10"}
+	end
+	
+	
 	targetdir "../../bin"
 	
 	initOpenCL(vendor)