Fix some issues when loading new-format scenarios

- Carriage returns misinterpreted as map features
- Error code returned by CopyFiles
- Confusing error message when a file is missing in the archive

pkg/win/build-scen.bat

@@ -0,0 +1,9 @@
+
+set Zip="C:\Program Files\7-Zip\7z.exe"
+
+@echo Packing scenario %2...
+if exist %2 del /F %2
+if exist %2 exit 1
+move %1 scenario
+%Zip% a -ttar -so temp.tar scenario | %Zip% a -tgzip -si %2
+move scenario %1