Imported existing sources

sketchlib/container/triangle.cpp

@@ -0,0 +1,11 @@
+#include "triangle.h"
+
+Triangle::Triangle(QObject *parent) :
+    Layer(parent)
+{
+}
+
+bool Triangle::parseProperty(const QString &key, const QJsonValue &value)
+{
+    return Layer::parseProperty(key, value);
+}