The first parameter is required, and is a wxArrayString. The list of files
will be put into this array. OnFile and OnDir are optional, and are cdecl callbacks
used by the traverser:
- OnFile: This function is called for each file. It may return wxDIR_STOP
to abort traversing (for example, if the file being searched is found) or wxDIR_CONTINUE to proceed.
- OnDir: This function is called for each directory. It may return wxDIR_STOP to abort
traversing completely, wxDIR_IGNORE to skip this directory but continue with others or
wxDIR_CONTINUE to enumerate all files and subdirectories in this directory.
The defaults are files that always return wxDIR_CONTINUE. OnFile adds each file name
to the wxArrayString