1. wxGrid row can't be resized to less than minimal height

1. wxGrid row can't be resized to less than minimal height
2. memory leaks fixed in wxHashTableLong
3. and in wxGrid
4. changed newgrid sample to use char buffers
5. fixed double clicking owner-drawn buttons
6. compilation fix in enhmeta.cpp for !wxUSE_DND
7. bug introduced earlier today in wxGridCellAttr::GetEditor() fixed
8. bool renderer/editor now look as good as I may ever make them look
   good under MSW

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@6391 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775