v1.3.1 - refactor(sequence+selector): pass through errors unmodified

Error values will no longer be munged by Sequence or Selector. Previously, error messages were prefixed to include the child index. This behavior has proven itself to range from fairly useless to actively detrimental, due to log spam that may be generated, e.g. when propagating an error upwards through a large tree.

I also noticed I had flipped the comments somehow, oops.