Add GameState::EditAllowedForExtra metric.

Docs/Changelog_sm5.txt

@@ -11,6 +11,9 @@ StepMania 5.0 $next | 201110??
 2011/09/29
 ----------
 * [Fallback theme] Fix ImmediateHoldLetGo function. [Wolfman2000]
+* [GameState] Add the EditAllowedForExtra metric. Use this if you want edit
+  steps to be allowed for accessing the extra stage. By default, this is
+  false. [Wolfman2000]
 
 2011/09/26
 ----------

Themes/_fallback/metrics.ini

@@ -490,6 +490,8 @@ LockExtraStageSelection=true
 # [sm-ssc] Normally, in event mode, the premium value is ignored. Set this
 # metric to true to re-gain that behavior.
 DisablePremiumInEventMode=false
+# Let edit steps be allowed for earning extra stages.
+EditAllowedForExtra=false
 
 [GrooveRadar]
 # Polar graph that shows difficulty stuff in depth

src/GameState.cpp

@@ -94,6 +94,7 @@ Song* GameState::GetDefaultSong() const
 	return sid.ToSong();
 }
 
+static const ThemeMetric<bool> EDIT_ALLOWED_FOR_EXTRA ("GameState","EditAllowedForExtra");
 static const ThemeMetric<Difficulty> MIN_DIFFICULTY_FOR_EXTRA	("GameState","MinDifficultyForExtra");
 static const ThemeMetric<Grade> GRADE_TIER_FOR_EXTRA_1	("GameState","GradeTierForExtra1");
 static const ThemeMetric<bool> ALLOW_EXTRA_2		("GameState","AllowExtra2");
@@ -1297,6 +1298,7 @@ EarnedExtraStage GameState::CalculateEarnedExtraStage() const
 		switch( dc )
 		{
 		case Difficulty_Edit:
+			if( !EDIT_ALLOWED_FOR_EXTRA )
 				continue; // can't use edit steps
 			break;
 		default: