Allow sounds to be preloaded and stopped.

Also, minor cleanup.
Play sounds on first-come-first-served basis by default.
Fix animation callback scheduling.
Add assets download handler to store setup method.
Better error logging.
Fix defect in sound-controller.

Instead of resetting the previous sound item,
reset the current one before playing. This fixes
issues where some sounds don't get reset and fail
to play.
Add array reverse helper.
v0.1.2
Harden sound playing.
Amend 080b75e, harden sound preloading.
Expose download-timeout on video-manager.
Harden optional SFX playback in effects macro.

Don't short if sound playback fails. Just fallback
to toggling without sound. Note the appended
option to avoid an infinite loop.
Clarify error message logging.
Minor constructor tweak.
Add active-downloads tracking to video-manager.
Add dismissal-block to toast-view.
Better debug logging.
Fix subpixel rendering on toast-view.
Add -isEqualToSelector for string category.

Also fill in missing pragma-marks.
Also require localVideoPath for videoable dao protocol.