Fix updator.bat casing bug, swap update-alert sound for a popup

updator.bat's assume-unchanged step compared "cosmic rage\worlds\cosmic
rage\cosmic rage.mcl" against git's actual tracked casing
(worlds\Cosmic Rage\cosmic rage.MCL) - git's index is case-sensitive
even on a case-insensitive filesystem, so `if exist` found the file
fine but `git update-index --assume-unchanged` couldn't match it,
producing the "Could not mark ... as assume-unchanged" warning. Fixed
the casing.

Also replaced the full-volume (100) announcement.ogg alert on an
outdated soundpack with a utils.msgbox popup - it was startling people
with no way to turn it down. Bonus: a native Windows dialog gets read
by screen readers automatically, which is arguably better for
accessibility than an unskippable sound cue anyway.

cosmic rage/worlds/plugins/CosmicRage.xml

@@ -115,7 +115,13 @@ Note("You are currently running version " .. tostring(CURRENT_SP_VERSION).." of
   if version_diff > 0 then
     ColourNote("yellow", "", "Warning: Your soundpack is " .. version_diff .. " version(s) out of date. We are now on version " .. user_version .. " of the soundpack.")
     ColourNote("yellow", "", "Launching the updater...")
-    ppi.play(dir.."sounds/ogg/general/comms/announcement.ogg", 0, 0, 100)
+    -- A popup instead of an audio alert here - the announcement sound
+    -- played at full volume (100) with no way to tune it down, which
+    -- startled people. This only fires once per outdated connect, so a
+    -- blocking dialog is fine.
+    utils.msgbox(
+      "Your soundpack is " .. version_diff .. " version(s) out of date.\n\nThe updater will now launch in a separate window. Once it finishes, restart MUSHclient to apply the update.",
+      "Soundpack update available", "ok", "!")
     -- dir is the world's own folder (cosmic rage\worlds\Cosmic Rage\);
     -- updator.bat lives at the repo root, three levels up from there.
     local bat_path = dir .. "..\\..\\..\\updator.bat"