Debug forms & --dotimes fix

Two patches in one because I'm lazy

1. Previously edebug couldn't step through the macro-forms, now it can (it's as if they were proper lambdas). I wasn't aware that `form` specification can do that, but apparently it can. I still can't fix `->>` though.

2. `--dotimes` evaluated the `num` argument `num` times, which is wrong if it's a form---it could even loop infinitely if it changed something by side effect.