fpspreadsheet: Fix bug 0026386 (in Excel, all sheets must be "active" and "selected"). New chm help file. Fix some issues with spready and fpsgrid due to range check errors. BiffExplorer shows detail info on SHEETPR record.

git-svn-id: http://svn.code.sf.net/p/lazarus-ccr/svn@3236 8e941d3f-bd1b-0410-a28a-d453659cc2b4