Module for standard type aliases

[benhutchison]

There are some very common refined types that it would be nice to give short, standardized names to.

Int Refined Positive and Int Refined NonNegative being two examples, which I found myself aliasing after using refined for about an hour.

Without standard names, different users will invariably choose different aliases to refer to the same refinement. Eg I chose NatInt and Nat0Int for the above two respectively, while Quasar apparently uses Positive and Natural.

Ideally this is done in a seperate modular layer, so people can opt in to the standard names but aren't forced to use them.

Gitter context: https://gitter.im/fthomas/refined?at=577cca9d9d3eadd723767548

[benhutchison]

Thanks @fthomas Im introducing these now to a codebase and finding them useful :)

[fthomas]

@benhutchison I'm very pleased to hear that! I'm currently working on #369 which hopefully makes working with type aliases easier.