Bug 55037: patch for missing function DELTA
 Add missing TestDeltaFunctionsFromSpreadsheet and register Delta in AnalysisToolPak

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1529809 13f79535-47bb-0310-9956-ffa450edef68
Bug 55081: patch for missing function WEEKNUM
Add simple spreadsheet with Excel 2003, and another with 2013 (both fresh files)

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1530256 13f79535-47bb-0310-9956-ffa450edef68
Add Eclipse Project Files.
Replace Vector to ArrayList.

Optimize String concatenate.