Refactored the MemoryOutputStream constructors and added some new features. Tidied up some stream methods to avoid relying on the stream length, which can be unreliable in http streams. Tweaked some mac atomic functions. Fixed some win32 dllexport declarations.

src/application/juce_ApplicationCommandTarget.cpp

@@ -37,6 +37,11 @@ ApplicationCommandTarget::ApplicationCommandTarget()
 }
 
 ApplicationCommandTarget::~ApplicationCommandTarget()
+{
+    releaseMessageListener();
+}
+
+void ApplicationCommandTarget::releaseMessageListener()
 {
     messageInvoker = 0;
 }