Add a target to help with generating the release notes

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1614573 13f79535-47bb-0310-9956-ffa450edef68
Change XSSFSheetXMLHandler.SheetContentsHandler to require fewer backwards incompatible changes for #56023

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1614576 13f79535-47bb-0310-9956-ffa450edef68