Merge from origin/emacs-26

Merge from origin/emacs-26

3e72298 Improve documentation of 'pcase-defmacro rx'
ba9b9bb Fix TTY colors breakage by 'clear-face-cache'
f56ad42 * admin/MAINTAINERS: Add files maintained by me (Michael Albi...
7a258fa Adapt shadowfile.el for Tramp  (Bug#4526, Bug#4846)
cb50077 Fix auth-source-delete (Bug#26184)
a4767a6 Avoid assertion violations in gnutls.c
90110f8 Don't use a literal "C-u" in ispell.el  help message text
f4e7f6d Improve documentation of 'seqp'
ed13639 Clarify usage and dependencies between several Flyspell features

Conflicts:
	etc/NEWS
	test/lisp/auth-source-tests.el