git move enhancements

[arxanas]

The following are needed in order to consider git move stable:

• Implement git restack in terms of git move.
  • Implemented in Reimplement git restack using RebasePlan machinery #49.
• Improve performance of in-memory git move on repositories with large indexes.
  • Implemented in in memory fast rebase #96
• Detect commit which have already been applied upstream and skip them.
  • Implemented in Don't reapply upstream commits #62, upstream applied #64, patch id #76.
• On-disk rebase should either handle or abort on merge commits.
  • Implemented in rebase merge commits #93.
• git move -b should use the merge-base with the destination OID, not just the main branch.
  • Implemented in 5db546a.
• In-memory rebases should be able to merge non-conflicting changes.
• On-disk git move needs to abort if there are working copy changes.
  • Implemented in git move improvements #67.

The following would be good to have afterwards:

• In-memory rebases should be able to merge conflicting changes, with user intervention.
• The default should be --base ., not --source ., the same as https://www.mercurial-scm.org/wiki/RebaseExtension.
  • Implemented in git move improvements #67

[arxanas]

git move was stabilized in v0.3.5. The remaining item, to resolve merge conflicts in-memory, would best be developed on top of a future UI for staging partial changes.