Default to Standards-Version: 3.9.5

Partly addresses #17. I guess adding an option for this would also be
nice.
New flag --standards-version

This closes #17, I believe.
Let utils packages depend on ${shlibs:Depends}

Also binary packages ought to depend on ${shlibs:Depends}, otherwise
they would miss the dependency on libffi6 or libgmp10. So change the
logic to explicitly exclude -prof and -doc from having this dependency.
This fixes #18.
Adjust handling of --revision to docs

According to --help, the revision needs to start with a dash, so parse
it that way.
Do not restrict the version on -prof and -doc build dependencies.

This fixes #13. Not configurable so far.
Do not indent Build-Depends so far

Partially implements #1. Still lacks a trailing comma.
Nicely pretty print build dependencies

with a trailing comma. This fixes #1.
Remove the hoogle entry to .links

and the accompagning command line option. This fixes #8.
Add an --official flag

and make it set the standards version, the homepage and the VCS fields.
This fixes #6 and #19.
Change default distribution to UNRELEASED

this fixes #15.