Add fancy hashing

src/utils/hash.hpp

@@ -0,0 +1,16 @@
+#ifndef HASH_HPP
+#define HASH_HPP
+
+#include <xxhash.h>
+#include <string>
+
+namespace dropshell {
+
+    XXH64_hash_t hash_file(const std::string &path);
+
+    XXH64_hash_t hash_directory_recursive(const std::string &path);
+
+} // namespace dropshell
+
+
+#endif