This adds EBDB, an EIEIO port (rewrite) of BBDB.

The package depends on cl-lib and seq.  I don’t see any mention of
cl-lib in emacs-xyz.scm, but I do see an ‘emacs-seq’ there, and it’s
used in propagated-inputs of three packages.  What’s the preferred way?
Is it fine to omit seq (and other Emacs Core packages that were also
added to GNU ELPA for users of older versions of Emacs), or would it be
best to explicitly add it in propagated-inputs?