[ESS] ess-jags-d alist

[Jack Tanner]

The manual says: "Model files with the .bug extension are edited in ESS[BUGS]
mode if (require 'ess-bugs-d) was performed or edited in ESS[JAGS] mode if
(require 'ess-jags-d)."

In 5.14 and in 12.03, if I do ess-jags-d, .bug files are not associated with
anything.