Fixed coding of a switch statement that had RETURN statements before the BREAK statem...

Fixed coding of a switch statement that had RETURN statements before the BREAK statements, causing compiler warnings with BCC
Initialized the temporary date variables so that if a date in the DB is corrupt, then the variables will have a default value in them.
When data sources list box is populated, if the DB specified in the .CFG file is no longer in the list, a wxASSERT() message was generated in debug builds.  Now the program makes sure that the datasource is in the listbox's choices before trying to set the selected choice to that string

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@12609 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775