New profiler, for profiling time spent in a function/block.

Profiling_tools/examples/Profiling_tools/Profile_timer.cpp

@@ -0,0 +1,15 @@
+#define CGAL_PROFILE
+
+#include <CGAL/Profile_timer.h>
+
+int main()
+{
+  CGAL_TIME_PROFILER("seconds spent in this for loop");
+  for (int i=0; i<10; ++i)
+  {
+    // do something
+    double d = 1+1;
+    (void) d;
+  }
+  return 0;
+}