Fractional numbers in greeklang 0.0.5

I’ve added initial specifications for working with fractional values in “Milesian” notation to the greeklang library: specifications for tokens in Milesian notation now covering integers, fractions, and compound expressions combining integers and fractions are here.

As previously noted, I’m leaving open for the moment the question of how to represent fractional values using ASCII-only characters, but now anyone who is happy with Unicode can compose integer and fractional values to a defined specification.