Fixed NumberCellRendererToString Method

Exeption was:
     ** 2014-04-08 13:49:45,113 [1] FATAL Sara Shell [(null)] - Method '.ctor' in type 'Decimal' : OverflowException : Value was either too large or to...
    System.OverflowException: Value was either too large or too small for a Decimal.
       at System.Decimal..ctor(Double value)
       at System.Double.System.IConvertible.ToDecimal(IFormatProvider provider)
       at System.Convert.ToDecimal(Object value)
       at XPTable.Renderers.NumberCellRenderer.OnPaint(PaintCellEventArgs e) in S:\xptable\xptable_git\Renderers\NumberCellRenderer.cs:line 656
       at XPTable.Renderers.CellRenderer.OnPaintCell(PaintCellEventArgs e) in S:\xptable\xptable_git\Renderers\CellRenderer.cs:line 583
       at XPTable.Renderers.NumberCellRenderer.OnPaintCell(PaintCellEventArgs e) in S:\xptable\xptable_git\Renderers\NumberCellRenderer.cs:line 600
       at XPTable.Models.Table.OnPaintCell(PaintEventArgs e, Int32 row, Int32 column, Rectangle cellRect) in S:\xptable\xptable_git\Models\Table.cs:line 7878
       at XPTable.Models.Table.OnPaintRow(PaintEventArgs e, Int32 row, Rectangle rowRect) in S:\xptable\xptable_git\Models\Table.cs:line 8549
       at XPTable.Models.Table.OnPaintRows(PaintEventArgs e) in S:\xptable\xptable_git\Models\Table.cs:line 8458
       at XPTable.Models.Table.OnPaint(PaintEventArgs e) in S:\xptable\xptable_git\Models\Table.cs:line 7630
       at System.Windows.Forms.Control.PaintWithErrorHandling(PaintEventArgs e, Int16 layer)
       at System.Windows.Forms.Control.WmPaint(Message& m)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Description