Merge from origin/emacs-26

Merge from origin/emacs-26

643df63 (origin/emacs-26) Avoid byte-compiler warning in em-rebind.el
d0eca49 ; * doc/emacs/mark.texi (Disabled Transient Mark): Fix last c...
af80b10 Improve indexing of 'C-SPC C-SPC'
89a7301 ; * doc/lispref/internals.texi (Writing Dynamic Modules): Fix...
a108eaa Fix bug with precious entries in Gnus registry
ce8b458 Document in the ELisp manual how to write loadable modules
a7ebc6b dired-do-shell-command: Notify users after abort the command

# Conflicts:
#	lisp/registry.el