Fixed GAMESTATE:GetCurrentStage to use correct logic for determining if all human players are on final stage.

THEME:GetPath lua functions can now pass true for the third arg if the element is optional.
Fixes to various StageDisplay things in default.
thify_number and thified_curstage_index lua functions added to default/Scripts/04 Other.lua.

Themes/default/Scripts/04 Other.lua

@@ -17,4 +17,47 @@ function SongMeterDisplayCommand(pn)
 		local xAdd = (pn == PLAYER_1) and -24 or 24
 		return cmd(draworder,5;rotationz,-90;zoom,0;addx,xAdd;sleep,1.5;decelerate,0.5;zoom,1;addx,xAdd*-1)
 	end
-end
+end
+
+function thify_number(n)
+	if n >= 10 and n < 20 then return n .. "th" end
+	local th_suffixes= {"st", "nd", "rd"}
+	local end_digit= n % 10
+	return n .. (th_suffixes[end_digit] or "th")
+end
+
+local numbered_stages= {
+	Stage_1st= true,
+	Stage_2nd= true,
+	Stage_3rd= true,
+	Stage_4th= true,
+	Stage_5th= true,
+	Stage_6th= true,
+	Stage_Next= true,
+}
+
+function is_stage_final()
+	-- The correct way to determine whether the player has reached Final Stage
+	-- is to check the number of stages left.
+	-- If you use the SongsPerPlay preference, you become incorrect after a
+	-- continue occurs.
+	local master_player= GAMESTATE:GetMasterPlayerNumber()
+	local stages_left= GAMESTATE:GetNumStagesLeft(master_player)
+	local stage_cost= GAMESTATE:GetCurrentSong():GetStageCost()
+	return (stages_left - stage_cost) < 1
+end
+
+function thified_curstage_index(on_eval)
+	local cur_stage= GAMESTATE:GetCurrentStage()
+	local adjust= 1
+	-- hack: ScreenEvaluation shows the current stage, but it needs to show
+	-- the last stage instead.  Adjust the amount.
+	if on_eval then
+		adjust= 0
+	end
+	if numbered_stages[cur_stage] then
+		return thify_number(GAMESTATE:GetCurrentStageIndex() + adjust)
+	else
+		return ToEnumShortString(cur_stage)
+	end
+end