Release version 1.6.0.

Changes:

- Make dimmer more nvidia driver friendly, fixing a crash on large
  multi-monitor configurations by limiting the complexity of render calls;
  controlled using XSECURELOCK_DIM_MAX_FILL_SIZE.
- Add a weaker force-grab method that merely steals input focus;
  XSECURELOCK_FORCE_GRAB still controls the stronger method, but it should
  trigger less often now.
- Fix crash with colored emoji fonts (still can't render emoji; we're now
  simply rejecting fonts Xft cannot handle).
- Also run the switch user dialog on Ctrl-Alt-Zero as an alternative
  to Ctrl-Alt-Oh; more user friendly as in some fonts, Ctrl-Alt-O looks
  like both.
- XFlush when doing things affecting X11 idle timers.

Then we can safely show Ctrl+Alt+O on the screen :)

At least one user tried to press zero instead of oh; changed Ctrl-Alt-O
(upper case) to Ctrl-Alt-o (lower case) to disambiguate.

Should fix crash issues with nvidia driver.

Credit goes to tommie.

This doesn't make them work, we still need to switch to another font
renderer, but this fixes the crash of auth_x11 when using them.

See bug #83.

This already closes lots of context menus and makes the force grab code hit less.

Release version 1.5.1.

Changes:

- XSECURELOCK_FORCE_GRAB no longer sometimes fails to re-map the unmapped
  windows in case locking fails despite the forcing. Previously, a missing XSync
  call led to the re-mapping sometimes not taking effect.

Makes sure our and X11's idle timers are more consistent. Should normally
only have had a delta of below 100ms though (WATCH_CHILDREN_HZ is 10,
and XPending flushes).

Fixes "xsecurelock while slock is running may unmap all your windows".

No behavioral change.

That way, helpers can still expect to live in that directory.

INTERNAL_REFERENCE=140864646

Fixes "xsecurelock gets into non-unlockable state if Debian package is reinstalled/upgraded while the screen was locked".

INTERNAL_REFERENCE=140864646

Also, provide a general variable
(XSECURELOCK_ALLOW_LOCKING_IF_INEFFECTIVE) to bypass these checks,
when wanting to develop XSecureLock itself on a Chromebook (Wayland!) for
example.

Works around issues in third-party authentication modules.

Fixes #39.

Fixes #81.

This shouldn't be necessary but may work around graphics driver bugs.

Fixes #80.

For now they're C99-only; possibly to be fixed later.

Also, fix plurals of -moji words.