[enh] add basic node finder feature
[mod] make position in rendering dict absolute
[enh] stop searching if target line is passed

This means that the targetted column is out of range on the right
[enh] allow non-list dependency in rendering dict
[enh] add nodes to rendering dict
[mod] pep8
[mod] remove dead code
[mod] split big function into multiple ones
[mod] avoid useless test
[mod] internal use of object to handle path
[mod] move render function in its own file
[mod] extract node walker from finder purpose

Both have different goal.
[mod] remove unused function
[mod] reduce indirection of walker
[mod] get rid of useless StopState class
[mod] separate walking and working concepts
[mod] remove useless class for walking tree
[mod] add worker functions when descending tree
[mod] move formatting keys handling in worker
[mod] begin rendering keys indexing at 0