Re: async I/O API: why strings?

[Krux02]

@vega how does `seq[byte]` deal any more with GC as `string` deals with GC? I 
recommend to use something similar to 
[MemSlice](http://forum.nim-lang.org///nim-lang.org/docs/memfiles.html#MemSlice).
 Sadly both words range and slice have already been occupied by the `system` 
module.