implemented effect copying/pasting

io/clipboard.cpp

@@ -1,4 +1,17 @@
 #include "clipboard.h"
 
+#include "project/clip.h"
+
 int clipboard_type = CLIPBOARD_TYPE_CLIP;
 QVector<void*> clipboard;
+
+void clear_clipboard() {
+    for (int i=0;i<clipboard.size();i++) {
+        if (clipboard_type == CLIPBOARD_TYPE_CLIP) {
+            delete static_cast<Clip*>(clipboard.at(i));
+        } else if (clipboard_type == CLIPBOARD_TYPE_EFFECT) {
+            delete static_cast<Effect*>(clipboard.at(i));
+        }
+    }
+    clipboard.clear();
+}