Fixes after merge weirdness from pull request (specifically, removed `bfrandom' from "mpfr.rkt" again)
Removed dependence of math/flonum on math/bigfloat (better build parallelization)
Changed `divides?' to return #f when its first argument is 0
Made return type of `quadratic-character' more precise
Made argument types more permissive:
* second argument to `solve-chinese'
* second argument to `next-primes'
* second argument to `prev-primes'
in the original GitHub fork:
https://github.com/ntoronto/racket
Some things about this are known to be broken (most egregious is that the
array tests DO NOT RUN because of a problem in typed/rackunit), about half
has no coverage in the tests, and half has no documentation. Fixes and
docs are coming. This is committed now to allow others to find errors and
inconsistency in the things that appear to be working, and to give the
author a (rather incomplete) sense of closure.
