qt: use deleteLater to remove send entries

Use deleteLater() instead of delete, as it is not allowed
to delete widgets directly in an event handler.
Should solve the MacOSX random crashes on send with coincontrol.

Rebased-From: 6c98cca9e47ddb9c786cd3f0445175c378515e0d

src/qt/sendcoinsdialog.cpp

@@ -227,7 +227,7 @@ void SendCoinsDialog::clear()
     // Remove entries until only one left
     while(ui->entries->count())
     {
-        delete ui->entries->takeAt(0)->widget();
+        ui->entries->takeAt(0)->widget()->deleteLater();
     }
     addEntry();
 
@@ -286,7 +286,7 @@ void SendCoinsDialog::updateRemoveEnabled()
 
 void SendCoinsDialog::removeEntry(SendCoinsEntry* entry)
 {
-    delete entry;
+    entry->deleteLater();
     updateRemoveEnabled();
 }