Convert PDF Documents to RTF Documents
val cPDFConvert = CPDFConverterRtf(context, uri, "")
val params = CPDFConvertRtfOptions()
val result: ConvertError = cPDFConvert.convert(outputDir, outputFilenameNoSuffix, params, pageArrays,
onHandle = onHandleCal,
onProgress = onProgressCal,
onPost = onPostCal)