[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
[mod] use rendering_dictionary in dumper
[enh] export rendering dictionnary
[mod] add defensive default case
[mod] do not mix class and functions in API
[mod] rely on explicit stop condition
[mod] split stop and found conditions
[mod] make PathHandler methods more explicit
[mod] simplify call of functions
[mod] move walker inside render module
[enh] render any node and walk close to dict structure
[mod] test validity of rendering_dictionnary
[mod] make sure the path doesn't point to a constant node