Correct serialization

Serialization does not seem to be working correctly, see unit tests below:

```
 FAIL  test/bitsy.test.js
  ✓ Checks if conversion of minimal.bitsy works correctly both ways. (23ms)
  ✕ Checks if conversion of red-dog-endless-spaceship.bitsy works correctly both ways. (31ms)
  ✕ Checks if old JSON from version 0.0.1 still gets serialized correctly. (26ms)
```
