Open an asset using ACCESS_STREAMING mode

Property definitions

android $ NativeAssetManager :: open
	# Open an asset using ACCESS_STREAMING mode
	fun open(file_name: JavaString): NativeInputStream in "Java" `{
		InputStream stream = null;
		try {
			stream = self.open(file_name);
		}catch (IOException e) {
			Log.e("Error while opening " + file_name, e.getMessage());
			return null;
		}
		return stream;
	`}
lib/android/assets_and_resources.nit:76,2--86,3