Merge branch 'en/ort-perf-batch-8'

Rename detection rework continues.

* en/ort-perf-batch-8:
  diffcore-rename: compute dir_rename_guess from dir_rename_counts
  diffcore-rename: limit dir_rename_counts computation to relevant dirs
  diffcore-rename: compute dir_rename_counts in stages
  diffcore-rename: extend cleanup_dir_rename_info()
  diffcore-rename: move dir_rename_counts into dir_rename_info struct
  diffcore-rename: add function for clearing dir_rename_count
  Move computation of dir_rename_count from merge-ort to diffcore-rename
  diffcore-rename: add a mapping of destination names to their indices
  diffcore-rename: provide basic implementation of idx_possible_rename()
  diffcore-rename: use directory rename guided basename comparisons

diff --cc Documentation/gitdiffcore.txt
Simple merge

diff --cc diffcore-rename.c
Simple merge

diff --cc diffcore.h
Simple merge

diff --cc merge-ort.c
Simple merge