Android: Asset/Resource refactoring for compatibility with other platforms. Other platforms are able to access the bundled assets via the filesystem. Android keeps the assets in the Zipped APK archive, so during initialization we now extract the non-resource (numeric images) into the app cache dir. dw_app_dir() now returns the path to the application cache. dw_user_dir() returns either the HOME directory or the path to the application root directory (usually the parent of the cache).

# Set these here to change the version for all platforms
DW_MAJOR_VERSION=3
DW_MINOR_VERSION=2