fpspreadsheet: Fix ODS reader crashing when finding unexpected nodes among row nodes (see http://forum.lazarus.freepascal.org/index.php/topic,25624.msg157029.html#msg157029). 
Fix the ODS reader detecting underlined font style for the file of this discussion. 
Fix incorrect row height calculation of TsWorksheetGrid introduced in the previous commit.

git-svn-id: http://svn.code.sf.net/p/lazarus-ccr/svn@3544 8e941d3f-bd1b-0410-a28a-d453659cc2b4