One of the three must always be specified, but they buried in a long list of
options in the output of --help. Make them more visible to draw the eye.
Also, drop "marked" from the description. It's supposed to mean "configured",
but it's a strange way to say that, and also it's generally obvious that the
program does what its configuration tells it to, and it's not going to remove
all files found on the system.
This adds a new script tools/check-version-history.py and a corresponding
test when building in developer mode. It checks manpages (except dbus
documentation which is handled by update-dbus-docs) for missing version
history information.
It also adds ignore lists based on version 183 (the version that our version
annotations go back to). These can be augmented if we want to ignore other
elements if it doesn't make sense for them to have version annotations.
