Move most tests into test submodules

  * all tests can be run by running run-tests.rkt
  * individual tests can be run with `raco test`
Merge branch 'test-submodules' of https://github.com/takikawa/rudybot into takikawa-test-submodules

Conflicts:
	xlate.rkt
Nix run-tests.rkt; instead, we'll use "raco test ."

One test is either failing, or acting weird:

    testing ./servers.rkt
    2013-03-04T01:38:49Z (re)loading module from irc-process-line.rkt
    2013-03-04T01:38:49Z error, module not reloaded (define-values: assignment disallowed;
     cannot re-define a constant
      constant: is-master?
      in module: "/home/erich/usr-local-src/rudybot/irc-process-line.rkt")
    2013-03-04T01:38:49Z (([running body] . #(struct:srcloc /home/erich/usr-local-src/rudybot/irc-process-line.rkt #f #f #f #f)) (auto-reload-procedure13 . #(struct:srcloc /home/erich/usr-local-src/rudybot/reloadable.rkt 44 0 1849 674)) ([running body] . #(struct:srcloc /home/erich/usr-local-src/rudybot/loop.rkt #f #f #f #f)) ([traversing imports] . #(struct:srcloc /home/erich/usr-local-src/rudybot/servers.rkt #f #f #f #f)) (loop . #(struct:srcloc /usr/local/racket/collects/compiler/commands/../../racket/private/map.rkt 53 19 1773 151)) ([running body] . #(struct:srcloc /usr/local/racket/collects/compiler/commands/test.rkt #f #f #f #f)) ([running body] . #(struct:srcloc /usr/local/racket/collects/raco/raco.rkt #f #f #f #f)) ([running body] . #(struct:srcloc /usr/local/racket/collects/raco/main.rkt #f #f #f #f)))
Whine about "raco test"
Merge branch 'test-cleanup'