Gnus: Automatically render text/calendar in a human-friendly way

* lisp/gnus/mm-decode.el (mm-inline-media-tests): Add text/calendar entry.
Use (fboundp 'device-sound-enabled-p) rather than fishing for features.
(mm-automatic-display): Add text/calendar entry.

* lisp/gnus/gnus-icalendar.el: Use lexical-binding.
Remove redundant :group args.
(gnus-icalendar-mm-inline): Add autoload cookie.
1 job for master in 51 minutes and 46 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
failed #1164
test-all

00:51:46

 
Name Stage Failure
failed
test-all Test
make[2]: *** [check-doit] Error 1
Makefile:313: recipe for target 'check-doit' failed
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:288: recipe for target 'check-expensive' failed
make[1]: Leaving directory '/builds/emacs/emacs/test'
make[1]: *** [check-expensive] Error 2
Makefile:962: recipe for target 'check-expensive' failed
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1