New classes:

public class Vintasoft.Imaging.Codecs.Encoders.XlsxEncoder	Defines an encoder for XLSX pages.
public class Vintasoft.Imaging.Codecs.Encoders.XlsxEncoderException	Represents error that occurs during saving XLSX file.

Changed classes:

Vintasoft.Imaging.Office.OpenXml.OpenXmlDocumentConverter
Added methods
	public static void ConvertXlsToXlsx(System.IO.Stream, System.IO.Stream)	Converts the XLS document to XLSX document.
	public static void ConvertXlsToXlsx(string, string)	Converts the XLS document to XLSX document.

Vintasoft.Imaging.Office.OpenXml.Editor.OpenXmlTextInfo
Changed properties
	public string Text { get ; set ; }	public Vintasoft.Imaging.Drawing.DrawingString Text { get ; set ; }
Changed constructors
	public void OpenXmlTextInfo(string)	public void OpenXmlTextInfo(Vintasoft.Imaging.Drawing.DrawingString)
	public void OpenXmlTextInfo(string, Vintasoft.Imaging.Office.OpenXml.Editor.OpenXmlTextProperties)	public void OpenXmlTextInfo(Vintasoft.Imaging.Drawing.DrawingString, Vintasoft.Imaging.Office.OpenXml.Editor.OpenXmlTextProperties)