0.1.1 first step towards expansion

This patch both fixes some problems in the previous release, as well as offering a step towards a bigger expansion.

• Some change in the functional representations:
  • Changed random number generation from randfn, a functional representation, to the realise() and realize() functions.
  • Changed probfn representation to be more specific: pmf or density
• Added the enframe suite of functions.
• Implement the beginnings of being able to specify your own distribution, with the set_ suite of functions, after making an empty distribution with dst().

Additionally, there's some internal rearrangement, where the get functions call the eval functions, not vice versa.