Attempting to clean up the feature activation syntax?

Currently, a feature activation in the manifest can include: "foo": activate the feature foo in the current package "dep:foo": activate the optional dependency foo "foo?/bar": if the optional dependency foo is activated, activate the feature bar within it "foo/bar": If foo is non-optional dependency, activate the feature "bar" within it If foo is an optional dependency, activate it, activate a feature named foo if present, and activate the feature bar On the command line with resolver = "2...