Make some changes

- Add new programs
- Add command line args
- Add Usage to guide user on how to use programs

src/utils.cpp

@@ -60,4 +60,14 @@ std::string dirname(const std::string &path)
     return path.substr(0, path.find_last_of("/"));
 }
 
+std::string concatpath(const std::string &left, const std::string &right)
+{
+    if (left.back() != '/' and right.front() != '/') {
+        return left + '/' + right;
+    }
+    else {
+        return left + right;
+    }
+}
+
 } // namespace utils