Documentation

Per-package preferences on the version. It is a soft constraint that the DependencyResolver should try to respect where possible. It consists of an InstalledPreference which says if we prefer versions of packages that are already installed. It also has (possibly multiple) PackageVersionPreferences which are suggested constraints on the version number. The resolver should try to use package versions that satisfy the maximum number of the suggested version constraints.

It is not specified if preferences on some packages are more important than others.