check-release.pl: add a verbose mode

This mode _already_ reports on the status, even if there have been no
commits since the last release.

This mode will be useful for chaining with prettify-status.pl.
prettify-status.pl: show warnings first
prettify-status: show warnings section as needed

If there are no warnings, do not put the "Warnings" section at all.
prettify-status: change section header to "Ahead"

This section declares the components whose development is ahead of the
last release. So let's use a more descriptive label than just "Status".
prettify-status: add CSS classes for sections

This gives greater control over the styling of each section.
prettify-status: add a lead column to the table

This will let us perform some shenanigans in the CSS.
prettify-status: report on up-to-date components

This works by looking for components with a reported commit count of 0,
since those components are currently up to date.

It will require calling check-release.pl with the --verbose flag to do
much of interest.
prettify-status: only show relevant sections

If nothing needs release, do not show the "Ahead" section.
If nothing is up to date, do not show the "Released" section.
prettify-status: be consistent with <li> newlines