Merge branch 'js/c-merge-recursive'

Merge branch 'js/c-merge-recursive'

* js/c-merge-recursive: (21 commits)
  discard_cache(): discard index, even if no file was mmap()ed
  merge-recur: do not die unnecessarily
  merge-recur: try to merge older merge bases first
  merge-recur: if there is no common ancestor, fake empty one
  merge-recur: do not setenv("GIT_INDEX_FILE")
  merge-recur: do not call git-write-tree
  merge-recursive: fix rename handling
  .gitignore: git-merge-recur is a built file.
  merge-recur: virtual commits shall never be parsed
  merge-recur: use the unpack_trees() interface instead of exec()ing read-tree
  merge-recur: fix thinko in unique_path()
  Makefile: git-merge-recur depends on xdiff libraries.
  merge-recur: Explain why sha_eq() and struct stage_data cannot go
  merge-recur: Cleanup last mixedCase variables...
  merge-recur: Fix compiler warning with -pedantic
  merge-recur: Remove dead code
  merge-recur: Get rid of debug code
  merge-recur: Convert variable names to lower_case
  Cumulative update of merge-recursive in C
  recur vs recursive: help testing without touching too many stuff.
  ...

This is an evil merge that removes TEST script from the toplevel.