~/.bin/deadlines: record what you're working on.

needs a different name. turns out i either want to record what i want to
be working on _next_ or how far i got with what i was working on last.

random different idea: a music client that allows scheduling operations
at different points in time (before/after current song/album/playlist,
at a specific point in time, lots of others probably). on a mobile
device this is achieved by long tapping on the thing you wanted to do.
(e.g long tap on "enqueue" -> enqueue at some point).