Removed three prompts:
1. The "really edit?" prompt. If you don't want to edit, you can just not make
any changes.
2. The "done?" loop. This seems unnecessary; we'll confirm afterward anyway.
3. The YAML checker. This removal could indeed make things inconvenient, since
your changes get thrown away if you make a YAML mistake. For the moment,
simplicity is taking priority.
Our built-in "diff"-like functionality is pretty good because it's aware of
beets' data structures and types. This makes it more legible, in my opinion,
than an ordinary textual diff. So for now, I'm making this the only option (in
the spirit of making the plugin as straightforward as humanly possible).
* Delete NamedTemporaryFiles once they are not needed on several functions
(change_objs(), vimdiff(), html()).
* Fix use of reserved word "id" on same_format().
* Colorize "really modify" prompt with action_default.
