`zkg remove` can remove depended upon package without confirmation

[bbannier]

If an installed packaged foo/A depends on another package foo/B (which would have been installed automatically), one can still execute zkg remove foo/B without being notified that one might break foo/A.

While the ability to uninstall packages like foo/B can be useful while e.g., testing updates to foo/B, it would still be great if zkg would give some indication that this operation breaks the install and would default to not performing the removal, e.g.,

$ zkg remove foo/B
The following packages will be REMOVED:
  /foo/B

Proceed? [Y/n]
Package /foo/B is required by /foo/A, remove anyway? [y/N]