This takes the responsibilty of finding the ipkg away from IDE mode,
which seems sensible given that we can do it ourselves. If there isn't
one, it'll load from the local directory as always.
Including appropriate casts, and Num/Eq/Ord/Show implementations.
Also includes new primitives in Data.Buffer, and calls to foreign
functions in C as 'unsigned'.
This means it abstracts over the value syntactically, rather than by
value, and can significantly speed up elaboration where large types are
involved, at a cost of being less general. Try it if "with" is slow.
There are more flags we want on with (well, at least one: "proof")
Still a couple of things to resolve in coverage and totality checking
before we can switch on %default, so don't expect quite the right
behaviour just yet. More progress though!
Also working on this has caught a few totality errors in the Idris 2
code base that Idris 1 missed... so these are fixed on the way.
