[packagekit] Getting the depends of a file

[Richard Hughes]

We're needing a function to get the depends of a set of files, not
packages, so we can offer to install packages from repos as deps when
we install local files. So far, I've got the following ideas:

1. GetDependsFile
2. GetFileDepends
3. GetFilesDepends
4. GetDependsFiles

Any other ideas or comments? I guess 3 or 4 makes most sense as we'll
be passing a string array of files, not a single file.

Richard.