New ScreenCapture separate from Device, with Window selection

For now only LINUX support for window selection. New icons for Loopback and for ScreenCapture. Important BugFix on DeviceSource and Device management.

src/Mixer.cpp

@@ -47,6 +47,7 @@
 #include "MediaSource.h"
 #include "PatternSource.h"
 #include "DeviceSource.h"
+#include "ScreenCaptureSource.h"
 #include "MultiFileSource.h"
 #include "StreamSource.h"
 #include "NetworkSource.h"
@@ -390,6 +391,18 @@ Source * Mixer::createSourceDevice(const std::string &namedevice)
     return s;
 }
 
+Source * Mixer::createSourceScreen(const std::string &namewindow)
+{
+    // ready to create a source
+    ScreenCaptureSource *s = new ScreenCaptureSource;
+    s->setWindow(namewindow);
+
+    // propose a new name based on pattern name
+    s->setName( namewindow.substr(0, namewindow.find(" ")) );
+
+    return s;
+}
+
 Source * Mixer::createSourceNetwork(const std::string &nameconnection)
 {
     // ready to create a source