fpspreadsheet: Improvments of TsWorksheetGrid and fpsgrid demo: Fix currency symbol not shown when selecting currency format. Fix showing a zero value when assigning a number format to an empty cell. Fix formula display when selecting an empty cell. Reset number format when selecting "General" format. Move selection to entered cell address in address edit.


git-svn-id: http://svn.code.sf.net/p/lazarus-ccr/svn@3144 8e941d3f-bd1b-0410-a28a-d453659cc2b4