Support complex renaming via 'rename' action of 'file' or 'dict' scheme

[lambdalisue]

This PR fix numerous rename issue on rename action of file and dict scheme.

Cases fern support

Simple renames

foo -> a
bar -> b

Nested renames

foo   -> bar
foo/a -> bar/b
foo/c -> bar/c

Cross renames

foo     -> a/foo
foo/a   -> a

Cyclic renames

foo -> bar
bar -> foo

Nested and Cyclic renames

a   -> b
a/b -> b/c
a/c -> b/b

Cases fern warn and avoid

Duplicate destinations

foo   -> bar
foo/a -> bar

Conflicts with exsiting file

foo   -> bar
foo/a -> bar/b

Above renames on the follwoing tree should be avoided before actual renames.

foo
|- a
|- b

Destination under non directory

foo   -> a/foo
foo/a -> a

Above fails if foo/a is file.

[lambdalisue]

NOTE: I have to check if this PR breaks behavior on Windows or not.