function parseInteger( raw, str ) {
	return new MultiSlice( parseInt( str, 10 ) );
}
Parses a serialized integer.

@private
@param {string} raw - original unprocessed input string
@param {string} str - serialized integer
@returns {MultiSlice} MultiSlice object

@example
var s = parseInteger( '  1  ', '1' );
// returns <MultiSlice>