Clean up generator state

include/internal/catch_context_impl.hpp

@@ -12,6 +12,7 @@
 
 #include "catch_context.h"
 #include "catch_stream.hpp"
+#include "catch_common.h"
 
 namespace Catch {
 
@@ -21,6 +22,11 @@ namespace Catch {
         Context( Context const& );
         void operator=( Context const& );
 
+    public:
+        virtual ~Context() {
+            deleteAllValues( m_generatorsByTestName );
+        }
+
     public: // IContext
         virtual IResultCapture* getResultCapture() {
             return m_resultCapture;