* lisp/whitespace.el (whitespace--empty-at-bob-matcher,
whitespace--empty-at-eob-matcher, whitespace--update-bob-eob,
whitespace-color-off, whitespace-color-on,
whitespace-empty-at-bob-regexp, whitespace-empty-at-eob-regexp,
whitespace-looking-back, whitespace-post-command-hook): Redo the
`empty' line highlighting logic to ensure that a buffer change causes
all affected `empty' lines to become (un)highlighted (bug#37467).
Also, for improved UX, don't highlight BoB empty lines at or below
point (not just when point is at 1), or EoB empty lines at or above
point (not just when point is `eobp').
(whitespace-bob-marker, whitespace-eob-marker): Clarify documentation.
* test/lisp/whitespace-tests.el (whitespace--with-test-buffer,
whitespace--fu, whitespace-tests--empty-bob,
whitespace-tests--empty-eob): Add tests.
Most of this change is to boilerplate commentary such as license URLs.
This change was prompted by ftp://ftp.gnu.org's going-away party,
planned for November. Change these FTP URLs to https://ftp.gnu.org
instead. Make similar changes for URLs to other organizations moving
away from FTP. Also, change HTTP to HTTPS for URLs to gnu.org and
fsf.org when this works, as this will further help defend against
man-in-the-middle attacks (for this part I omitted the MS-DOS and
MS-Windows sources and the test tarballs to keep the workload down).
HTTPS is not fully working to lists.gnu.org so I left those URLs alone
for now.
* lisp/whitespace.el (whitespace-display-char-on): Correct the way
the original buffer-display-table is saved and restored when
global-whitespace-mode is active. (Bug#26892)
* test/lisp/whitespace-tests.el
(whitespace-tests-whitespace-mode-on): New function.
(whitespace-tests-display-tables): New test.
Copyright-paperwork-exempt: yes
* lisp/whitespace.el (whitespace-empty-at-eob-regexp): Match any number
of empty lines at end of buffer.
* test/lisp/whitespace-tests.el (whitespace-cleanup-eob): New test.
(whitespace-tests--cleanup-string): New helper function for tests.
