changelog: add a couple of missing entry

evolve: strip the extra obsmarkers if any on `hg evolve --abort` Previous patches started storing some obsmarkers which needs to stripped during `evolve --abort` which can't be stripped by stripping the new evolved changesets because they point to a node which existed before the evolution was performed. This patch adds logic to strip those obsmarkers by finding their indices in the obsstore and then stripping them.

evolve: store the obsmarkers to be deleted in evolvestate Sometimes, we don't create a new node and obsolete one of the old node in favour of an existing node. When user calls, `hg evolve --abort`, we need to strip that obsmarker to go back in the same old state. The obsmarker created for new node are stripped when the new nodes are stripped. This patch start storing such obsmarkers in the evolvestate so that we can delete them later if required. Right now we just store successsor and predecessor information, we might need a better obsmarker serialization techinque in future to make it more robust.

evolve: store obsmarkers to be deleted in evolvestate There are operations which don't create a new node rather they just obsolete one of the unstable node in favour of existing one. In such cases if a further resolution leads to conflicts and user calls `evolve --abort` or `evolve --stop`, we might need to delete that obsmarker. So let's store such obsmarkers in the evolvestate.