fix hex package

update README to add example with new APIs

fix format_id for non binary attrs, default graph is directed, docs and bump version

refacto: not codec lib became too big, dotx is only facade

working version of to_nodes,to_edges,digraph graph handling

describe first iteration : nodes extractions

add file info

update package metadata and docs deps

add licence

clean lib: add doc and typespec, clean missing test and functions

fix flatten to handle {a b}->c a->c b->c

first commit