fix "unbound #%plain-module-begin" error in DrRacket w/ debugging

The instrumenter now local-expands the module body wrapped in a
This avoids triggering Racket's submodule-related binding bug
on the configure-runtime submodule introduced by Racket's
updated todo
added temperature field to {single,multi}-site
minor MH refactoring
fix dist-support for discrete-dist
fix mh-sampler: allow both kw args
add enumerative-gibbs MH transition
refactor define-dist-type macro

Define an aux macro define-fl-dist-type that contains the
old unhygienic parts.
split out private/dist-define.rkt
split dists into multiple modules
trim useless requires and defns
export and document define-dist-type
fix or/c case collision error in matrix types
fix inverse-gamma convenience function
add mixture-dist
added permutation dist code from Sean
use linear alg to generate permutation
require dist types to end with -dist
update todo; fixed bugs
update todo