Support for date range cleaning

[tzkmx]

I've come to this command looking for a programmable way to clean out revisions without resorting to plugins hooked to the request cycle through wp-cron events. It's very useful and I thank you for putting up onto this.

A nice enhancement has been proposed in the PR #2 from @alexisbellido, however the date filter could be applied to the traversal of the whole list of posts of the requested post_type, making the traversal faster.

I'm just filing this issue in order to take this proposal to you, I've forked the repo and I'm willing to make a PR later on this week.