Settings: Support LIBOPENSHOT_DEBUG envvar

- Setting LIBOPENSHOT_DEBUG to any value in the process environment
  activates debug logging to stderr.

src/Settings.cpp

@@ -28,14 +28,14 @@
  * along with OpenShot Library. If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <cstdlib>        // For std::getenv
+
 #include "Settings.h"
 
-using namespace std;
 using namespace openshot;
 
-
 // Global reference to Settings
-Settings *Settings::m_pInstance = NULL;
+Settings *Settings::m_pInstance = nullptr;
 
 // Create or Get an instance of the settings singleton
 Settings *Settings::Instance()
@@ -53,6 +53,9 @@ Settings *Settings::Instance()
 		m_pInstance->HW_EN_DEVICE_SET = 0;
 		m_pInstance->PLAYBACK_AUDIO_DEVICE_NAME = "";
 		m_pInstance->DEBUG_TO_STDERR = false;
+		auto env_debug = std::getenv("LIBOPENSHOT_DEBUG");
+		if (env_debug != nullptr)
+			m_pInstance->DEBUG_TO_STDERR = true;
 	}
 
 	return m_pInstance;

src/Settings.h

@@ -31,19 +31,7 @@
 #ifndef OPENSHOT_SETTINGS_H
 #define OPENSHOT_SETTINGS_H
 
-
-#include <iostream>
-#include <iomanip>
-#include <fstream>
-#include <cstdlib>
 #include <string>
-#include <sstream>
-#include <cstdio>
-#include <ctime>
-#include <zmq.hpp>
-#include <unistd.h>
-#include <OpenShotAudio.h>
-
 
 namespace openshot {
 
@@ -118,7 +106,7 @@ namespace openshot {
 		/// The current install path of OpenShot (needs to be set when using Timeline(path), since certain
 		/// paths depend on the location of OpenShot transitions and files)
 		std::string PATH_OPENSHOT_INSTALL = "";
-    
+
  		/// Whether to dump ZeroMQ debug messages to stderr
 		bool DEBUG_TO_STDERR = false;