Enhancement - statistics

- Added total data file size to statistics report.
- Implemented util.cpp/formatBytes.

src/util.h

@@ -54,6 +54,7 @@ bool confirm (const std::string&);
 void delay (float);
 std::string formatSeconds (time_t);
 std::string formatSecondsCompact (time_t);
+std::string formatBytes (size_t);
 int autoComplete (const std::string&, const std::vector<std::string>&, std::vector<std::string>&);
 const std::string uuid ();
 int convertDuration (const std::string&);