Most people would probably be able to work out this rather simple method for having your characters regenerate MP whilst they're not in battle, but I figured putting this here would help encourage people to use it. It's rather simple.
All you need to do is create a Parallel Process and enter this into the event:
>Restore MP: Full Party: +1
>Wait: 1.0 Sec
Then just ensure you put the event on every map you wish to have regeneration on. Simple...