Add fx components 291-320 and the home scene; Kit.Shot, Kit.Toward

Palette cycling, sky, sun and moon, clouds, starfield, rain, snow,
petals, leaves, fireflies, waterfall, ocean, campfire, lava, aurora,
lightning, mountains and a season scene; scanlines, vignette, screen
shake, flash, dither fades, iris wipes, dissolves, mosaics, glitches,
sparkles, explosions and confetti. Home opens on a live scene in the
palette's season and a strip of all eight palettes.

pixel adds Canvas.Cycled, Sprite.At, SpriteOf, Kit.Toward and
Kit.Shot, which spends a cue under Reduce Motion so it never replays;
display exports Reduce. Gallery grids and the sidebar are one Tab
stop each.

overlay/panels_test.go

@@ -54,6 +54,25 @@ func TestDrawerSlidesInInSteps(t *testing.T) {
 	}
 }
 
+func TestDrawerOpenedUnderReduceMotionNeverSlides(t *testing.T) {
+	clk, open := newClock(), false
+	tt := view(640, 400, clk, false, func(c *ui.Context) {
+		overlay.Drawer(c, "Menu", &open, overlay.DrawerOptions{Side: display.Right, Size: 100}, func() {
+			pixel.Text(c, "Items", pixel.TextOptions{})
+		})
+	})
+	tt.SetPreferences(ui.Preferences{ReduceMotion: true, TextScale: 1})
+	open = true
+	// At rest the panel's text sits at 640-200+16.
+	for _, reduce := range []bool{true, false} {
+		tt.SetPreferences(ui.Preferences{ReduceMotion: reduce, TextScale: 1})
+		tt.Frame()
+		if x := find(t, tt, "Items").X; x != 456 {
+			t.Fatalf("reduce %v: the drawer's text is at %v", reduce, x)
+		}
+	}
+}
+
 func TestSheetClosesOnALongPull(t *testing.T) {
 	open, closed := true, 0
 	tt := view(640, 400, newClock(), false, func(c *ui.Context) {