obsfate: fix obsfate_printer with empty date list When the list of dates is empty, `min` and `max` would raises a ValueError. Protect against this case by checking that the date list is not empty. I didn't add a test because I couldn't find a reproducing test case.

config: gather allowdivergence under the evolution namespace Grouping all evolution related-config under the experimental.evolution namespace would helps the future migration outside [experimental]. Differential Revision: https://phab.mercurial-scm.org/D1155

config: remove stabilization.* aliases Stabilization config items were never part of a release, remove them now that we cleaned up the evolution related configuration. Differential Revision: https://phab.mercurial-scm.org/D1154

config: rename stabilization.track-operation We want to get rid of stabilization.* configuration, back out to the old configuration 'evolution.track-operation'. Differential Revision: https://phab.mercurial-scm.org/D1153

config: rename stabilization.bundle-obsmarker We want to get rid of stabilization.* configuration, back out to the old configuration 'evolution.bundle-obsmarker'. Differential Revision: https://phab.mercurial-scm.org/D1152

config: use 'experimental.evolution.exchange' Extract 'experimental.evolution' = exchange as 'experimental.evolution.exchange'. We keep the new option in the 'experimental.evolution' namespace in order to stay coherent with other options ('experimental.evolution.bundle-obsmarker' and 'experimental.evolution.track-operation') ease the renaming as possibly 'evolution.exchange'. Differential Revision: https://phab.mercurial-scm.org/D1151