Moving headers into include/sls (#212)

sample/time.cpp

@@ -3,10 +3,10 @@
 #include <string>
 #include <memory>
 
-#include "Result.h"
-#include "Detector.h"
-#include "container_utils.h"
-#include "ToString.h"
+#include "sls/Result.h"
+#include "sls/Detector.h"
+#include "sls/container_utils.h"
+#include "sls/ToString.h"
 #include <algorithm>
 
 std::chrono::nanoseconds to_nano(double val, const std::string &unit) {