config: update evolution-related config Update the evolution helpers function to support both old-style configuration and new-style configuration: experimental.evolution=all is renamed into experimental.evolution=true experimental.evolution=createmarkers is renamed into experimental.evolution.createmarkers=true experimental.evolution=allowunstable is renamed into experimental.evolution.allowunstable=true experimental.evolution=exchange is renamed into experimental.evolution.exchange=true We choose to not rename individual config options; keeping the same names would easy the transition for users but it's something that could be easily done in the future. Differential Revision: https://phab.mercurial-scm.org/D1147