Check filenames for --save-* for forbidden characters.


Add tests for --save-*.


Release 2.5.0.


Open all files in binary mode. Output os.linesep instead of '\n'.


Add option -I to completely skip (remove) subparts -- no headers, no body,
nothing.


Extend options -eIi to multipart subparts.


Never touch multipart/encrypted and multipart/signed (but allow -I).


Convert dates to the current locale and timezone (with an option?)


Allow -d and -p accept shell-like patterns and/or regular expressions:
-d content-*,-content-*-encoding


Add option --save-as='%format' to generate names for --save-* files. Develop
a DSL to conditionally use values of headers, parameters and the counter.