Codechange: Use unique_ptr for fios company properties.

This is the data used to show company names in the saveload window.

src/fios.h

@@ -25,7 +25,7 @@ enum SaveLoadInvalidateWindowData {
 	SLIWD_FILTER_CHANGES,        ///< The filename filter has changed (via the editbox)
 };
 
-using CompanyPropertiesMap = std::map<uint, CompanyProperties *>;
+using CompanyPropertiesMap = std::map<uint, std::unique_ptr<CompanyProperties>>;
 
 /**
  * Container for loading in mode SL_LOAD_CHECK.