Updated patch from Marc from #55927 - handle date formulas too

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1614696 13f79535-47bb-0310-9956-ffa450edef68
Correct the mimetype in svn for test spreadsheet files

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1614697 13f79535-47bb-0310-9956-ffa450edef68
More Excel test file mimetypes in svn

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1614699 13f79535-47bb-0310-9956-ffa450edef68
More mimetype updates

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1614700 13f79535-47bb-0310-9956-ffa450edef68
SVN mimetypes for PowerPoint files

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1614701 13f79535-47bb-0310-9956-ffa450edef68
SVN mimetypes for Word files

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1614705 13f79535-47bb-0310-9956-ffa450edef68
Convert the test to using interfaces

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1614715 13f79535-47bb-0310-9956-ffa450edef68