Fixed some warnings, set -Wall, -Wextra

src/files/WorldFiles.h

@@ -3,9 +3,7 @@
 
 #include <map>
 #include <unordered_map>
-#ifndef std::string
 #include <string>
-#endif
 class Player;
 
 #define REGION_SIZE_BIT 5

src/files/files.h

@@ -1,9 +1,7 @@
 #ifndef FILES_FILES_H_
 #define FILES_FILES_H_
 
-#ifndef std::string
 #include <string>
-#endif
 
 extern bool write_binary_file(std::string filename, const char* data, size_t size);
 extern unsigned int append_binary_file(std::string filename, const char* data, size_t size);