Adding OTG and embedded host to 16U firmware

Now, I've never been clear on why something like a USB memory stick needs a fully conformant USB host to talk to it; if that's all you want to do.

I doubt that Arduino would want to add something officially that was not spec compliant but a minimalistic subset that would allow a relatively slow mass storage device like a flash stick is all I'm interested in.

For my needs if it only refused all but mass storage and only implemented the slower write operations it mean I could make a data logger without adding a sheild and doubling the basic hardware cost.