Allow more combinations of key themes?

[aspiers]

Currently it seems that you cannot have (say) both the lispy and paredit themes activated at the same time when setting lispy-key-theme via the Custom variable interface, because it's defined like this:

  :type
  '(set
    (const special)
    (radio
     (const lispy)
     (const paredit)
     (const evilcp))
    (const c-digits)
    (const oleh))

However both of these themes offer unique bindings which are very useful and nicely complementary. So I find that the following gives me a perfect combination:

(lispy-set-key-theme '(special paredit lispy c-digits))

So maybe something like the following type definition would be less restrictive and still relatively sane:

:type
  '(repeat
    (choice
     (const special)
     (const lispy)
     (const paredit)
     (const evilcp)
     (const c-digits)
     (const oleh)))

See also #556.