insert a row takes an unexpected long time

Steps to Reproduce

1. run the attached zul

Current Result

it takes over 60s to show the page

Expected Result

speed up the performance

Debug Information

• One cause: unnecessary cell change
  in FormulaTunerHelper.extendCellRef(),
  sheet3!E4
  the original formula: VLOOKUP(C4,sheet1!C:I,6,0)
  the formula after insertion: VLOOKUP(C4,sheet1!C$1:I$65537,6,0)
  The 2 formula are actually equivalent but their string are not equal (!fexpr.getFormulaString().equals(exprAfter.getFormulaString())) is false, it triggers cell change and calling getDependent() which takes a long time.
• In FormulaEngineEx.adjustPtgs():
  Ptg[] tokens = org.zkoss.poi.ss.formula.Formula.create(fe.getPtgs()).getTokens();
  it only copies 2 bytes whose max value is 65535 (Excel97) but PtgShifter runs with EXCEL2007 which has larger max row. Such create() will reduce the max row to 65535