修复内存泄漏；对空段落项目符号容错处理

ware/TSNumberingWare.tsf

@@ -21,6 +21,7 @@ begin
     ilvl := ppr.NumPr.Ilvl.Val;
     pstyle := ppr.PStyle.Val;
     num := numbering_adapter_.NumId(num_id);
+    if ifnil(num) then return array("", nil);
     abstract_id := num.AbstractNumId.Val;
     abstract_num := numbering_adapter_.AbstractNumId(abstract_id);
     lvls := abstract_num.Lvls();

ware/TSSectWare.tsf

@@ -1,7 +1,9 @@
 type TSSectWare = class
 public
     function Create();
+    function Destroy();
     function Do();
+    function AddElement(element: tslobj);
 
 public
     Elements: array of tslobj;
@@ -25,3 +27,8 @@ begin
     // println("Top = {}, Right = {}, Bottom = {}, Left = {}, Header = {}, Footer = {}\n",
     //     self.SectPr.PgMar.Top, self.SectPr.PgMar.Right, self.SectPr.PgMar.Bottom, self.SectPr.PgMar.Left, self.SectPr.PgMar.Header, self.SectPr.PgMar.Footer);
 end;
+
+function TSSectWare.AddElement(element: tslobj);
+begin
+    Elements[length(Elements)] := element;
+end;