Task Duration Enhancement

I understand I can change the constraints of a task at the individual task level, or at the project level if I use a template. I would like to be able to set the constraint on a project without using a template, and without doing it individually on tasks. Please add this as an enhancement for future release.

For example, I'd like to be able to calculate start date, end date, and duration is these three ways:

1. Duration and Start date = calculate End date (existing functionality)
2. Duration and End date = calculate Start date (existing functionality)
3. Start and End dates = calculate duration (requested functionality)