[PATCH v4 0/10] port tag.c to use ref-filter APIs

This is part of my GSoC project to unify git tag -l, git branch -l,
git for-each-ref.  This patch series is continued from: Git (next)
https://github.com/git/git/commit/bf5418f49ff0cebc6e5ce04ad1417e1a47c81b61

Version 3 can be found here
http://thread.gmane.org/gmane.comp.version-control.git/274168

Changes from v3:

[01/10]: Changed the whole implementation as per Junio's Suggestion.
Also fixed parts where the code was wrong, as per Matthieu's and
Eric's suggestion.

[04/10]: Small changes in comments and line wrapping.

[05/10]: Include more tests, better comments and refactored code.

[06/10]: Improvement in comments.

[09/10]: Change the tests to not fallback to default values.
Introduce "for_each_tag_ref_fullpath()" which iterates through tags
without stripping the same.

[10/10]: Improvements in comments.

Set of commits:

[PATCH v4 01/10] ref-filter: add option to align atoms to the left
[PATCH v4 02/10] ref-filter: make the 'color' use
[PATCH v4 03/10] ref-filter: add option to filter only tags
[PATCH v4 04/10] ref-filter: support printing N lines from tag
[PATCH v4 05/10] ref-filter: add support to sort by version
[PATCH v4 06/10] ref-filter: add option to match literal pattern
[PATCH v4 07/10] tag.c: use 'ref-filter' data structures
[PATCH v4 08/10] tag.c: use 'ref-filter' APIs
[PATCH v4 09/10] tag.c: implement '--format' option
[PATCH v4 10/10] tag.c: implement '--merged' and '--no-merged'