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

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