Merge branch 'jt/repo-structure'

"git repo structure", a new command.

* jt/repo-structure:
  builtin/repo: add progress meter for structure stats
  builtin/repo: add keyvalue and nul format for structure stats
  builtin/repo: add object counts in structure output
  builtin/repo: introduce structure subcommand
  ref-filter: export ref_kind_from_refname()
  ref-filter: allow NULL filter pattern
  builtin/repo: rename repo_info() to cmd_repo_info()

Author: gitster

Documentation/git-repo.adoc

@@ -9,6 +9,7 @@ SYNOPSIS
 --------
 [synopsis]
 git repo info [--format=(keyvalue|nul)] [-z] [<key>...]
+git repo structure [--format=(table|keyvalue|nul)]
 
 DESCRIPTION
 -----------
@@ -43,6 +44,35 @@ supported:
 +
 `-z` is an alias for `--format=nul`.
 
+`structure [--format=(table|keyvalue|nul)]`::
+	Retrieve statistics about the current repository structure. The
+	following kinds of information are reported:
++
+* Reference counts categorized by type
+* Reachable object counts categorized by type
+
++
+The output format can be chosen through the flag `--format`. Three formats are
+supported:
++
+`table`:::
+	Outputs repository stats in a human-friendly table. This format may
+	change and is not intended for machine parsing. This is the default
+	format.
+
+`keyvalue`:::
+	Each line of output contains a key-value pair for a repository stat.
+	The '=' character is used to delimit between the key and the value.
+	Values containing "unusual" characters are quoted as explained for the
+	configuration variable `core.quotePath` (see linkgit:git-config[1]).
+
+`nul`:::
+	Similar to `keyvalue`, but uses a NUL character to delimit between
+	key-value pairs instead of a newline. Also uses a newline character as
+	the delimiter between the key and value instead of '='. Unlike the
+	`keyvalue` format, values containing "unusual" characters are never
+	quoted.
+
 INFO KEYS
 ---------
 In order to obtain a set of values from `git repo info`, you should provide