function trim( str ) {
	return replace( str, RE, '$1' );
}
Trims whitespace characters from the beginning and end of a string.

@private
@param {string} str - input string
@returns {string} trimmed string

@example
var out = trim( '   Whitespace   ' );
// returns 'Whitespace'

@example
var out = trim( '\t\t\tTabs\t\t\t' );
// returns 'Tabs'

@example
var out = trim( '\n\n\nNew Lines\n\n\n' );
// returns 'New Lines'