naming options

[jimspoon]

Suggestions:
(1) more options for naming subfolder to contain the attachments - if subfolder can be given same name as the EML file (without eml extension), it will be easier to know which EML the attachment belongs to.
(2) currently, if two emls have the same subject line, the attachments will be placed together in the same folder, which may not be wanted
(3) if the emls also have the same attachment file name, user will be prompted to overwrite the attachment file that was first saved.
(2) if --recursive option is used, would be good if attachments subfolder was placed in the same folder as the eml file being processed.