Packages should list all direct dependencies in their ups table files

We have been allowing developers to list as many or as few direct dependencies as they wish in the ups file of a package, as long as the chain of dependencies includes everything needed. I propose that we recommend that every package list all direct dependencies in the ups file because:

• It is more robust against changes in dependent packages. If package A depends on B and C, and B depends on C, then it is sufficient for A to only list B as a dependency. But if B is later changed to not rely on C then this breaks A in a way that is surprising.
• It makes the dependencies of the package explicit to readers of the code.
• It reduces the need to understand the dependency tree of dependent packages.

This is clearly a contentious issue so I am directly assigning it to K-T