Restore lines saying "Maintainer: emacs-devel@gnu.org" when there is
no special maintainer for a file. Although this wasn't documented
it was common practice and removing the lines didn't have consensus.
Update some other copyright years automatically, by running:
Run 'UPDATE_COPYRIGHT_YEAR=2019 \
UPDATE_COPYRIGHT_USE_INTERVALS=1 \
UPDATE_COPYRIGHT_MAX_LINE_LENGTH=79 admin/update-copyright'
followed by 'admin/merge-gnulib'.
* src/eval.c (backtrace_thread_p, backtrace_thread_top)
(backtrace_thread_next, Fbacktrace_frames_from_thread): New functions.
* lisp/thread.el (thread-list-mode-map): Add keybinding and
menu item for 'thread-list-pop-to-backtrace'.
(thread-list-mode): Make "Thread Name" column wide enough
for the result of printing a thread with no name with 'prin1'.
(thread-list--get-entries): Use 'thread-list--name'.
(thread-list--send-signal): Remove unnecessary calls to 'threadp'.
(thread-list-backtrace--thread): New variable.
(thread-list-pop-to-backtrace): New command.
(thread-list-backtrace--revert-hook-function)
(thread-list--make-backtrace-frame)
(thread-list-backtrace--insert-header, thread-list--name): New
functions.
* lisp/thread.el (thread-list--timer-func): Change
argument from 'buf' to 'buffer'.
(thread-list--get-entries, thread-list--get-status): Improve
docstring.
(thread-list--send-signal): Change argument from 'sgnl' to
'signal'. Tell the user when the thread is no longer alive.
