Remove dos/unix conversion

Commands fromdos and todos (formerly dos2unix and unix2dos) are not
very useful and can be called from a terminal instead.
They usually need to be executed once, and will not be used anymore
afterwards.

Signed-off-by: Cédric Marie <cedric.marie@openmailbox.org>
Display a message when updating all files (F5)

Add messages to show that the update of open files is in progress, and
when it is finished.
It is also useful when there are not so many open files, and the update
is so fast that we need to get a confirmation that it was really
performed.

Signed-off-by: Cédric Marie <cedric.marie@openmailbox.org>