Changed additive gravity behavior for main TGM modes

tetris/modes/marathon_a1.lua

@@ -33,6 +33,7 @@ function MarathonA1Game:new()
 	
 	self.randomizer = History4RollsRandomizer()
 
+	self.additive_gravity = false
 	self.lock_drop = false
 	self.enable_hard_drop = false
 	self.enable_hold = false

tetris/modes/marathon_a2.lua

@@ -34,6 +34,7 @@ function MarathonA2Game:new()
 		"GM"
 	}
 
+	self.additive_gravity = false
 	self.lock_drop = false
 	self.lock_hard_drop = false
 	self.enable_hold = false

tetris/modes/marathon_a3.lua

@@ -39,6 +39,7 @@ self.SGnames = {
 		"GM"
 	}
 	
+	self.additive_gravity = false
 	self.lock_drop = true
 	self.lock_hard_drop = true
 	self.enable_hold = true