Change distance evaluation period from Sessions to Blocks (nodes/rust/duniter-v2s!252)

* update metadata

* rename echec in failure

* fix nodes/rust/duniter-v2s#174

* replace session by pool

* fix nodes/rust/duniter-v2s#207

* update client

* update distance-oracle

* update documentation

* add weight accounting

* fix end2end tests

* make tests independent of EvaluationPeriod

* change distance evaluation period from Sessions to Blocks