Merge branch 'ds/include-exclude'

Merge branch 'ds/include-exclude'

The internal code originally invented for ".gitignore" processing
got reshuffled and renamed to make it less tied to "excluding" and
stress more that it is about "matching", as it has been reused for
things like sparse checkout specification that want to check if a
path is "included".

* ds/include-exclude:
  unpack-trees: rename 'is_excluded_from_list()'
  treewide: rename 'exclude' methods to 'pattern'
  treewide: rename 'EXCL_FLAG_' to 'PATTERN_FLAG_'
  treewide: rename 'struct exclude_list' to 'struct pattern_list'
  treewide: rename 'struct exclude' to 'struct path_pattern'