(#3) Switched back to *.c for screen implementation

Author: s1hofmann

src/screen.cc renamed to src/screen.c

@@ -1,6 +1,6 @@
 #include "screen.h"
 #include "os.h"
-#include "window.h"
+#include "highlightwindow.h"
 
 #if defined(IS_MACOSX)
 	#include <ApplicationServices/ApplicationServices.h>
@@ -34,6 +34,5 @@ bool pointVisibleOnMainDisplay(MMPoint point)
 }
 
 void highlight(int x, int y, int width, int height, int duration, float opacity) {
-    Window highlightWindow(x, y, width, height);
-	highlightWindow.show(duration, opacity);
+	showHighlightWindow(x, y, width, height, duration, opacity);
 }