Rename Stat struct

[ViralBShah]

When using Gadfly, I get:

Warning: using Base.Stat in module Stat conflicts with an existing identifier.

It would be nice to leave the name Stat for other purposes.

[StefanKarpinski]

It may also be possible to make this warning go away.

[StefanKarpinski]

In particular, if the name of the module is bound after the implicit using Base then this wouldn't happen.

[StefanKarpinski]

I still think the binding order should change and/or the warning shouldn't happen, no?

[JeffBezanson]

That was fixed in a separate issue.

[StefanKarpinski]

Right, I forgot if that had happened or not.