More dot syntax //FREEBIE

The war on square brackets continues. A lot fewer chain reactions now, where I spot candidates as I fix candidates.

As usual, using regex replaces like `\[([^\[\]]*) (mutable[^ :\]]*)\]` to `$1.$2` (interestingly, `\1.\2` no longer works in the latest version of xcode) combined with manual checking.
Oh, this non-dot-syntax change snuck in.