This seems necessary in some cases; for some reason _this week_ that came
up a few time, although the code is old. Could repro with a bare emacs.

Fixes #2683.

We can't do much about them; still attempt to show the message.

Fixes #2561.

mu4e--view-render-buffer: Disable Gnus bookmark-make-record-function

The function 'gnus-summary-bookmark-make-record' does not work properly with the
faux "appeasement" summary buffer, causing undesired changes in the window
configuration when the message rendering buffer's bookmark function is
called (which some packages, like Activities, Burly, and Dogears do routinely).

See <https://github.com/alphapapa/activities.el/issues/55>.

Reported-by: Daniel Goldin <https://github.com/danielgoldin>

mu4e: add support for macOS notifications

The current order in this patch is

1) macos notification
2) built-in dbus notification
3) fallback text notification

because macOS emacs can actually have dbus enabled (for emacs daemon
mode) but that doesn't support notifications. This is a built-in way to
send a simple notification for macs, too. Yay!

Some external programs (such as bbdb) seems to depend on that.