Merge from origin/emacs-26

Merge from origin/emacs-26

070e82b ; * src/window.c (window_scroll): Improve commentary.
60457d7 Improve documentation of the window tree
ea1a014 Fix window scrolling on TTY frames when there's no mode line
df7ed10 Fix decoding XML files encoded in ISO-8859
7851ae8 (tag: emacs-26.1.90) ; ChangeLog.3 update
1958808 * etc/AUTHORS: Update.
7252507 Fix description of some window hooks
88762b4 Run 'window--adjust-process-windows' when frame size changes ...
d6542ea Avoid errors in zone.el when there's overlay at EOB