== DETAILS
After running this script and inadvertently nuking my fork, I've
added a safety check so that it doesn't happen to anyone else.
Change summary:
- update the .gitignore to ignore wiiu artifacts and Mac OSX junk files
- add two command-line parameters to `retroarch-release.sh`:
* `--clean` will execute the legacy behavior of deleting and re-
cloning `libretro/RetroArch`
* `--force` will execute the release script using the current
state of `retroarch/` without re-cloning, although it will still
do a `git pull` and fetch submodules.
If neither argument is provided, then the script fails with
instructions if it detects that the `retroarch/` directory already
exists.
