Ascii Memcache Codec

Hi folks,

this is a work in progress, but it already came very far. The only integral missing piece is the decoder which I need to handle with care if I want to get it performant (because the ASCII protocol is a PITA to decode).

I wanted to get early feedback from you first to see if I'm on the right track w.r.t. to structure before I implement the decoder.

Also don't focus on docs and formatting yet, need to document and format the whole thing once all is in there, so I don't have to do it twice :)

Curious what you think,
Cheers
Michael