input.conf: make Alt+BS reset --video-align-{x,y}

This is useful because positioning.lua uses video-align.

etc/input.conf

@@ -69,7 +69,7 @@
 #Alt+KP_SUBTRACT add video-zoom -0.1    # zoom out
 #Ctrl+WHEEL_UP   add video-zoom  0.1    # zoom in
 #Ctrl+WHEEL_DOWN add video-zoom -0.1    # zoom out
-#Alt+BS set video-zoom 0; no-osd set panscan 0; no-osd set video-pan-x 0; no-osd set video-pan-y 0 # reset zoom and pan settings
+#Alt+BS set video-zoom 0; no-osd set panscan 0; no-osd set video-pan-x 0; no-osd set video-pan-y 0; no-osd set video-align-x 0; no-osd set video-align-y 0 # reset zoom and pan settings
 #HOME seek 0 absolute                   # seek to the start
 #PGUP add chapter 1                     # seek to the next chapter
 #PGDWN add chapter -1                   # seek to the previous chapter