Fix "tazered" monster not regenerating.

Fixes #6640

I simply moved code from `monster::move` (which is only called when the monster has move points left) into `monster::process_effects` (this is called once turn, regardless of the move points). The ability to regenerate seems much more like a effect anyway. The moved code does monster regeneration, damage from sunlight and moral regeneration.

There is another design problem (or maybe not?): the tazer iuse function does not add an effect, but removes move points of the monster. This leads to the monster having a relatively huge amount of negative move points. But that seems to be intended.