added gpl header to all source files

ui/rectangleselect.h

@@ -1,8 +1,39 @@
+/***
+
+    Olive - Non-Linear Video Editor
+    Copyright (C) 2019  Olive Team
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
 #ifndef RECTANGLESELECT_H
 #define RECTANGLESELECT_H
 
 #include <QPainter>
 
+/**
+ * @brief Routine for drawing a drag selection rectangle for any given QPainter
+ *
+ * @param painter
+ *
+ * QPainter object to use for drawing
+ *
+ * @param rect
+ *
+ * Rectangle to draw
+ */
 void draw_selection_rectangle(QPainter& painter, const QRect& rect);
 
 #endif // RECTANGLESELECT_H