restructure and add ipi texs

ws2019/ipi/uebungen/cpp_headers/timestamp.cc

@@ -0,0 +1,10 @@
+#include <ctime>
+// Setzt Marke und gibt Zeitdifferenz zur letzten Marke zurueck
+clock_t last_time;
+double time_stamp () {
+    clock_t current_time = clock();
+    double duration =
+        ((double)(current_time-last_time)) / CLOCKS_PER_SEC;
+    last_time = current_time;
+    return duration;
+}