Main: force UTF-8 locale.

src/main.cpp

@@ -25,6 +25,13 @@
 #include "SaveTool/SaveTool.h"
 
 int main(int argc, char** argv) {
+    auto str = std::setlocale(LC_ALL, ".utf-8");
+    if(str && !Containers::StringView{str}.hasSuffix(".utf8")) {
+        SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Error",
+                                 "Your system doesn't support UTF-8.", nullptr);
+        return EXIT_FAILURE;
+    }
+
     #ifndef SAVETOOL_DEBUG_BUILD
     std::ofstream output{"SaveToolLog.txt", std::ios::trunc|std::ios::out};