`animateMain` segfaults when running from repl

It (most probably) has something to do with addition of STM channels for events/render outputs. When compiled both apps run fine.

Note about cabal & ghci & RTS:
```
cabal exec ghci +RTS -N -qg
```

Start by reproducing the failure in animateMain through the documented command, cabal exec ghci +RTS -N -qg, and compare it with the compiled applications that run successfully. Investigate the STM channels for events and render outputs mentioned in the issue; done means the REPL invocation no longer segfaults.

Scritto dal modello di indicizzazione a partire dal testo della issue.