Add multi-selection context menu

fix compile errors on Mac and provide reviewed changes

fix wrong resolved conflict

removed duplicate

cleanup after latest merged PRs

minor cleanup

rename and move get_existing_dir() to File.cpp

apply reviewed changes

Utilities/File.h

@@ -195,6 +195,9 @@ namespace fs
 		return std::string{get_parent_dir_view(path, parent_level)};
 	}
 
+	// Return "path" plus an ending delimiter (if missing) if "path" is an existing directory. Otherwise, an empty string
+	std::string get_path_if_dir(const std::string& path);
+
 	// Get file information
 	bool get_stat(const std::string& path, stat_t& info);