Added option to read data with nanosecond timestamps

sensors/offline/FileReader.h

@@ -71,6 +71,8 @@ namespace Offline {
 
 		static constexpr char sep = ';';
 
+        bool convertNanoSecondTimestamps = true;  // otherwise use milliseconds
+
 	public:
 
 		/** empty ctor. call open() */
@@ -83,6 +85,13 @@ namespace Offline {
 			open(file);
 		}
 
+        /** ctor with filename */
+        FileReader(const std::string& file, bool convertNanoSecondTimestamps)
+          : convertNanoSecondTimestamps(convertNanoSecondTimestamps)
+        {
+            open(file);
+        }
+
 		/** open the given file */
 		void open(const std::string& file) {
 			clear();
@@ -192,6 +201,12 @@ namespace Offline {
 				sline >> delim;
 				sline >> data;		// might be "" if there is no data
 
+                if (convertNanoSecondTimestamps)
+                {
+                    ts /= 1000000;
+                }
+                
+
 				if		(idx == (int)Sensor::WIFI)			{parseWiFi(ts, data);}
 				else if	(idx == (int)Sensor::BEACON)		{parseBeacons(ts, data);}
 				else if	(idx == (int)Sensor::GROUND_TRUTH)	{parseGroundTruth(ts, data);}