Adds TextMesh variable anchor support to snap behaviors.
Adds MusicManager#fadePlay.

Adds a fade-in function and adds function arguments to specify fade
times on `fadePlay` and `fadeStop`.
Fixes X/Y swapped bug in Screen2D.js.
Move splash screen farther afield on click.
Widens aspect ratio for timer grid.
Adds text assets in MissionPack.js.
Adds functional level timer.

Tweens level timer into place.
Need to implement fail on level timer expiry.