Releases: manage time allocated and over-time (features for issue estimates available to releases)

We would like to be able to allocate "working days" ("original estimates") to a release (as we can now do with issues). Then, it would be useful, in some views (roadmap, open issues) to display columns showing working time planned for a release and time currently planned for the issues of this release. This could make it obvious that a release planned for some date already has too many issues assigned to it and that some issues need to be moved to later releases.