Beginnings of a WH40K.EXE implementation

So far, we just play the opening credits on an external video player.
I want to start loading and displaying the menus next. Perhaps I can
get the entire non-gameplay flow working?

internal/wh40k/videos.go

@@ -0,0 +1,36 @@
+package wh40k
+
+import (
+	"log"
+	"os/exec"
+)
+
+func (w *WH40K) PlayVideo(name string, skippable bool) {
+	// TODO: allow the video to be skipped by pressing the ESC key or so. For
+	// now, skip unconditionally
+	if skippable {
+		log.Printf("TODO: Make videos conditionally skippable")
+		return
+	}
+
+	filename := w.Config.DataFile("SMK/" + name + ".smk")
+
+	if len(w.Config.VideoPlayer) == 0 {
+		log.Printf("Video player not configured, skipping video %v", filename)
+		return
+	}
+
+	argc := w.Config.VideoPlayer[0]
+	argv := append(w.Config.VideoPlayer[1:], filename)
+	if err := exec.Command(argc, argv...).Run(); err != nil {
+		log.Printf("Error playing video %v: %v", filename, err)
+	}
+}
+
+func (w *WH40K) PlayUnskippableVideo(name string) {
+	w.PlayVideo(name, false)
+}
+
+func (w *WH40K) PlaySkippableVideo(name string) {
+	w.PlayVideo(name, true)
+}