upgrade to hoplon 5.10.1

- Improve brepl connection script injection
  For Hoplon apps, the connection script must be appended to the
  existing hoplon init <script...> section.
  For normal clojure apps, appending a separate <script...> is
  preferred.

- hoplon's ns generation no longer includes a gensym, update README
add :pass-through option to repl task
move brepl init code from :custom-eval to middleware

- init script needs to be in an initialization middleware so that
  jumping into the cljs repl happens when clients connect, not on nrepl
  server init
- put init script side effects in a delay (instead of a function) so
  they happen once per process
brepl html instrumentation on temporary source files
brepl example task

TODO: break out repl/repl and cljs repl tasks into two separate
projects.