stream a file backwards
exact same api as fs.createReadStream except reads chunks backwards. similar to fs-reverse except doesnt parse lines.
Stream data from start to end. if start is less than end they are switched rather then just not being useful.
var backwardsStream =var s =s
[1 2 3 4 5 6 7 8 9 10 11 12 13 14]start of file <---- end of file
where to start reading. defaults to the end of the file