优化堆叠模式体验，微调难度和评级

parts/eventsets/stack_e.lua

@@ -0,0 +1,20 @@
+return{
+    fillClear=false,
+    mesDisp=function(P)
+        setFont(60)
+        mStr(P.stat.row,63,280)
+        mText(TEXTOBJ.line,63,350)
+    end,
+    dropPiece=function(P)
+        if #P.field>P.gameEnv.fieldH then
+            local cc=P:clearFilledLines(P.garbageBeneath+1,#P.field-P.garbageBeneath)
+            local h=math.ceil((P.gameEnv.fieldH-cc-P.garbageBeneath)/2)
+            if h>0 then
+                P:garbageRise(21,h,2e10-1)
+                if P.garbageBeneath>=P.gameEnv.fieldH then
+                    P:lose()
+                end
+            end
+        end
+    end,
+}