there is no newline after the final mime boundary. (Bug#4539)
Move markers on insertion so that any buttons inserted don't end up in
the next part of a multipart message.
+ (rmail-mime-media-type-handlers-alist): Doc fix. Add image handler.
+ (rmail-mime-bulk-handler): Optionally handle images.
+ (rmail-mime-image): New button action.
+ (rmail-mime-image-handler): New function.
+ (rmail-mime-mode): New mode.
+ (rmail-mime): Doc fix. Use rmail-mime-mode (for font-lock).
2009-09-24 Stefan Monnier <monnier@iro.umontreal.ca>