match: fold plan cases down to two special cases - merge always and match with patterns - make always and match with patterns the default - invert dostep3 to skipstep3 - move dirignore test inside exact case

walk: refactor walk plan - never is gone - reorder tests more cleanly - rename nomatches to exact for clearer semantics

match: remove match.never Only one user, can be translated to match.exact()

walk: use match.bad callback for filetype messages

match: ignore return of match.bad All users returned false, return can now be dropped

add: use match.bad callback more effectively

match: document bad callback semantics

walk: simplify logic for badfn clause - matchfn redundant - call badfn always rather than fwarn - use for/else rather than keep var

walk: we always have a badfn

walk: simplify check for missing file