Merge branch 'jj/icase-directory' into next

Merge branch 'jj/icase-directory' into next

* jj/icase-directory:
  Support case folding in git fast-import when core.ignorecase=true
  Support case folding for git add when core.ignorecase=true
  Add case insensitivity support when using git ls-files
  Add case insensitivity support for directories when using git status
  Case insensitivity support for .gitignore via core.ignorecase
  Add string comparison functions that respect the ignore_case variable.
  Makefile & configure: add a NO_FNMATCH_CASEFOLD flag
  Makefile & configure: add a NO_FNMATCH flag

Conflicts:
	Makefile
	config.mak.in
	configure.ac
	fast-import.c