File installer for Windows and Mac

Develop software for Windows and Mac. The software will (a) bundle files into a one-click installer (b) copy these files to the filesystem when executed 1. For Windows, the installer will copy files to a location determined by the user using a 'browse' button, e.g. c:\program files\some_folder\target_directory 2. For Mac, the installer will programatically copy files into an existing app determined by the user, e.g. [login to view URL] > Show package contents > some_directory/target_directory Ideally the software will make it easy for us to bundle files in future without having to recompile every time we want to bundle new files. Some documentation detailing how to build and compile the software should be provided. The exact processes, languages and tools used will be at your suggestion - the merits and disadvantages of any particular approach should be made clear during our initial discussions, however the ideal solution, if possible, will be cross-platform so that we only need to work with one codebase in future. You should be comfortable working with adult / pornographic content and able to deliver in a timely fashion.