fpspreadsheet: Add more details on DEFINEDNAME record to BIFFExplorer; add details on EXTERN* records; fix compilation issue with TIpHTMLPanel.

git-svn-id: http://svn.code.sf.net/p/lazarus-ccr/svn@3483 8e941d3f-bd1b-0410-a28a-d453659cc2b4