update readme.txt
update Release note for 2.1.3.1
remove unnecessary file
update assembly version to 2.1.0.0 prepare for the release
2.0.6 RC1
fix some bugs a. XSSFSheet.ForceFormulaRecalculation = false doesn't work b. implement IsActive c. fix a bug in XSSFSheet.TopRow
fix hashtable comparison in HSSFCellUtil
2.0 beta2 RC1
NPOI 2.0 beta 1