Merge branch 'kn/for-each-tag'

The "ref-filter" code was taught about many parts of what "tag -l"
does and then "tag -l" is being reimplemented in terms of "ref-filter".

* kn/for-each-tag:
  tag.c: implement '--merged' and '--no-merged' options
  tag.c: implement '--format' option
  tag.c: use 'ref-filter' APIs
  tag.c: use 'ref-filter' data structures
  ref-filter: add option to match literal pattern
  ref-filter: add support to sort by version
  ref-filter: add support for %(contents:lines=X)
  ref-filter: add option to filter out tags, branches and remotes
  ref-filter: implement an `align` atom
  ref-filter: introduce match_atom_name()
  ref-filter: introduce handler function for each atom
  utf8: add function to align a string into given strbuf
  ref-filter: introduce ref_formatting_state and ref_formatting_stack
  ref-filter: move `struct atom_value` to ref-filter.c
  strtoul_ui: reject negative values

git-compat-util.h

@@ -814,6 +814,9 @@ static inline int strtoul_ui(char const *s, int base, unsigned int *result)
 	char *p;
 
 	errno = 0;
+	/* negative values would be accepted by strtoul */
+	if (strchr(s, '-'))
+		return -1;
 	ul = strtoul(s, &p, base);
 	if (errno || *p || p == s || (unsigned int) ul != ul)
 		return -1;