Initial attempt at dw_app_dir() for OS/2, Windows and Mac... This function will return the best attempt at determining the application data directory for the current platform. The executable directory on OS/2 or Windows. The application bundle directory on Mac. The "share" folder at the same level as the binary (or /usr/local/share if that can't be determined) plus the binary name on Unix.

# Set these here to change the version for all platforms
DW_MAJOR_VERSION=2
DW_MINOR_VERSION=2