fpspreadsheet: Extend TBufStream for reading. Rename workbook's WritingOptions to Options, and the option flags from woXXXX to boXXXX. Use boBufStream (former woBufStream) to activate TBufStream for reading of xls and ods. Speed up reading of biff2 by factor 3 (rel to  commit before prev one). Fix pile-up of temporary files when saving ods.

git-svn-id: http://svn.code.sf.net/p/lazarus-ccr/svn@3357 8e941d3f-bd1b-0410-a28a-d453659cc2b4