richmemo: wrap SetRangeParams range changes into BeginUpdate/EndUpdate. Making sure that no updates would be visibile as well as refreshing by the end of the change

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@5059 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/richmemo/richmemo.pas

@@ -867,6 +867,8 @@ begin
     Exit;
   end;
 
+  Lines.BeginUpdate;
+  try
     // manually looping from text ranges and re-applying
     // all the style. changing only the ones that in the mask
     i := TextStart;
@@ -888,6 +890,9 @@ begin
       SetTextAttributes(i, l, p);
       inc(i, l);
     end;
+  finally
+    Lines.EndUpdate
+  end;
 end;
 
 procedure TCustomRichMemo.SetRangeParaParams(TextStart, TextLength: Integer;