Display a standard browse for folder dialog

subroutine OS_BrowseFolder(string: Primary_Window_Name,

                           string: Comment_For_Browse_Dialog,

                           string: Full_Folder_Path)

Primary_Window_Name must contain the name of the program's primary region.

The dialog's title bar always contains the text "Browse For Folder", however, you may set the comment that appears within the dialog.

The selected directory's path is returned in Full_Folder Path, which will be blank if the User cancels the dialog or the Primary Window Name is invalid.