Don't indent inside comments, but allow as an option.

See issue #15.

This mostly works, but it falls in one corner-case:

```
;|
```

press enter:

```
                                        ;
|
```

It's not clear to me which code makes aggressive-indent modify the current line. Is this a bug in how `-internal-dont-indent-if` works?

------

A few thoughts on names.el, if it's helpful to you:

The approach works well, and I found the rules easy to grok (names are replaced except in quoted sections).

I managed to hack on the code, but it was harder than usual. Once I found `names-eval-defun` matters improved considerably. I think names-dev.el should autoload its functions, as they're less discoverable otherwise.

Still, a lot of my usual elisp tooling doesn't work. I can't use elisp-slime-nav to jump to a definition. I can't use highlight-symbol-next to jump between definition and usage of a variable or function.

There's a weird effect with `M-:`. If I press TAB I get the message:

    [names] No :package given. Guessing `aggressive-indent'

However, this is just a message from tab-completion. `M-:` doesn't understand the current namespace. Perhaps it should. Either way, I think chatty tab completion is confusing.

Hope that's useful.