Ensured that in wxFileDialog for opening existing file, default file is not set unless last opened file still exists.
Ensured that in wxFileDialog for opening existing file, default file is not set unless last opened file still exists.

git-svn-id: 0231d2b9506727b8389b50bfeac72ec1f38c13c1@1334 ac3cbfda-f6ac-4daa-b570-d46c5f00fc98

skybaboon/dailycashmanager,skybaboon/dailycashmanager,skybaboon/dailycashmanager