Do some more file format spelunking

`WarHammer.ani` turns out to be a regular `obj` file; `WarHammer.idx`
is partially decoded, but I'm struggling to link it to the former in
a reasonable way at the moment.

cmd/view-obj/main.go

@@ -17,6 +17,7 @@ var (
 	gamePath = flag.String("game-path", "./orig", "Path to a WH40K: Chaos Gate installation")
 	objFile  = flag.String("obj-file", "", "Path of an .obj file, e.g. ./orig/Obj/TZEENTCH.OBJ")
 	objName  = flag.String("obj-name", "", "Name of an .obj file, e.g. TZEENTCH")
+	sprIdx   = flag.Int("spr-idx", 0, "Sprite index to start at")
 
 	winX = flag.Int("win-x", 1280, "Pre-scaled window X dimension")
 	winY = flag.Int("win-y", 1024, "Pre-scaled window Y dimension")
@@ -62,8 +63,9 @@ func main() {
 	}
 
 	state := state{
-		zoom:   6.0,
-		origin: image.Point{0, 0},
+		zoom:      6.0,
+		origin:    image.Point{0, 0},
+		spriteIdx: *sprIdx,
 	}
 
 	env := &env{