Smarter animation delays + UI popups with a "hourglass"

[codemime]

Overview

Sometimes the game appears to be hanging for no apparent reason, but it, actually, isn't. The main reason of the "hangs" is invisible animation (if it's enabled, of course). It's invisible either to the player's alter ego or to the player themselves (because it's played beyond the screen bounds). Here are some frequent examples:

• An automatic turret is shooting at zombies behind the corner.
• A massive explosion somewhere indoors.
• Either of the above, taking place beyond the screen bounds.

This PR mitigates (if not resolves) the issue.

Observable behavior

• Invisible animations aren't played (no delays).
• Visible animations are followed by animated popups.

• The popups were added to the following:
  • explosions
  • shooting / throwing
  • sleeping
  • "death monitor"
• There was a noticeable "hang" after starting sleeping. It was there because the screen gets redrawn only after 30 ingame minutes. Now it's redrawn immediately.
• There was also flicker in the "death monitor" mode. Now the flicker has gone as well.

Implementation details

Nothing so exciting.

[Leland]

This is weird but: with these changes the box displayed on the active tile when examining isn't shown. I'm running this on a Mac – it's visible on master but not here.

[pisskop]

those delays are big hints that trouble is afoot nearby. perhaps an onscreen warning or something more noticeable than one line of text on the hud log?

[Coolthulhu]

those delays are big hints that trouble is afoot nearby.

Delays shouldn't be happening for things that are not seen. A line in the log describing the skipped delay would be fine, but relying on delay to convey any information is inherently wrong.