Pkg::Tree -> DepTree

This is fairly generic dependency-graphing stuff, not specific to Pkgs.

	renamed:    lib/Kodiak/Pkg/Tree.pm -> lib/Kodiak/DepTree.pm
	renamed:    lib/Kodiak/Pkg/Tree/Node.pm -> lib/Kodiak/DepTree/Node.pm
	modified:   lib/Kodiak/Pkg/Parser.pm
	modified:   lib/Kodiak/Pkg/Parser/Kodi.pm
	modified:   t/03_depgraph/tree.t