Added Refresh to wxGrid::EndBatch().
Use batch mode in sample.
Changed CalcDimension to better handle cases with zero columns or rows.
No more automatic insertion of column when adding rows to a grid without
columns.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_2_BRANCH@6947 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775