fixing crashes, adding threadsafety and changing welcome.,php

src/client_backend/md5hash.h

@@ -4,6 +4,8 @@
 #include <iostream>
 #include <fstream>
 #include <string>
+#include <mutex>
+#include <unordered_map>
 int md5_file(const char* path, char* md5Hash);
 //char* md5_file_t(const char* path_);
 std::string md5_file_t(const std::string& path_);