Pelmet 0.3.0-beta.2

Second beta of 0.3.0, on the beta channel only (Settings › About › "Get beta releases", 0.2.41 or later). Everything from beta.1, plus:

New:

• Running a beta build turns "Get beta releases" on for you, once, so a
  beta downloaded from GitHub keeps getting betas. Turning it off later is
  respected.

• A keyboard shortcut for Notification Center, ⌥⌘N, under the clock toggle
  in the Menu Bar tab. macOS's own shortcut is refused while icons are
  hidden, so Pelmet offers one that handles it the way a clock click does,
  the pointer stays put (#44, thanks @robinhur).

Fixed:

• A clock click kept the bar's picture up for a second or more before the
  hidden icons were back out of sight. Two of those waits were Pelmet's own
  and are gone: the picture now lifts the moment the bar is quiet, about
  0.7s after a click and 0.45s after the shortcut (#46, thanks
  @ldngoc-misa).

• The screen-recording indicator lit up while windows moved, with the bar
  untouched: a window sliding near the bar retook the bar's picture at
  once, about 40 times for every reveal that read it on a four-display Mac.
  The stale picture is still dropped, the new one is taken when the pointer
  heads for the bar, and the reveal waits for it if it is still in flight
  (#49, thanks @robinhur).

• A clock click while icons are hidden took a fresh picture of the bar,
  sometimes two, lighting the indicator at the moment of the click. The
  picture Pelmet already holds now spans the click's cover, so the click
  cuts its cover out of it and takes none, about 15ms instead of 150–450
  (#45, #46, PR #50, thanks @robinhur).

• A window that comes and goes under the bar, Notification Center most of
  all, no longer costs a new picture: the dropped one is kept and returns
  the moment the bar looks as it did.