Merge branch 'nd/columns'

A couple of commands learn --column option to produce columnar output.

By Nguyễn Thái Ngọc Duy (9) and Zbigniew Jędrzejewski-Szmek (1)
* nd/columns:
  tag: add --column
  column: support piping stdout to external git-column process
  status: add --column
  branch: add --column
  help: reuse print_columns() for help -a
  column: add dense layout support
  t9002: work around shells that are unable to set COLUMNS to 1
  column: add columnar layout
  Stop starting pager recursively
  Add column layout skeleton and git-column
diff --git a/builtin/help.c b/builtin/help.c
index e63668a..43d3c84 100644
--- a/builtin/help.c
+++ b/builtin/help.c
@@ -9,6 +9,7 @@
 #include "common-cmds.h"
 #include "parse-options.h"
 #include "run-command.h"
+#include "column.h"
 #include "help.h"
 
 static struct man_viewer_list {
@@ -30,6 +31,7 @@
 };
 
 static int show_all = 0;
+static unsigned int colopts;
 static enum help_format help_format = HELP_FORMAT_NONE;
 static struct option builtin_help_options[] = {
 	OPT_BOOLEAN('a', "all", &show_all, "print all available commands"),
@@ -251,6 +253,8 @@
 
 static int git_help_config(const char *var, const char *value, void *cb)
 {
+	if (!prefixcmp(var, "column."))
+		return git_column_config(var, value, "help", &colopts);
 	if (!strcmp(var, "help.format")) {
 		if (!value)
 			return config_error_nonbool(var);
@@ -424,8 +428,9 @@
 	parsed_help_format = help_format;
 
 	if (show_all) {
+		git_config(git_help_config, NULL);
 		printf(_("usage: %s%s"), _(git_usage_string), "\n\n");
-		list_commands(&main_cmds, &other_cmds);
+		list_commands(colopts, &main_cmds, &other_cmds);
 		printf("%s\n", _(git_more_info_string));
 		return 0;
 	}