Add a 'stats' page to each repo

This new page, which is disabled by default, can be used to print some
statistics about the number of commits per period in the repository,
where period can be either weeks, months, quarters or years.

The function can be activated globally by setting 'enable-stats=1' in
cgitrc and disabled for individual repos by setting 'repo.enable-stats=0'.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

cmd.c

@@ -21,6 +21,7 @@
 #include "ui-refs.h"
 #include "ui-repolist.h"
 #include "ui-snapshot.h"
+#include "ui-stats.h"
 #include "ui-summary.h"
 #include "ui-tag.h"
 #include "ui-tree.h"
@@ -109,6 +110,14 @@ static void snapshot_fn(struct cgit_context *ctx)
 			    ctx->repo->snapshots, ctx->qry.nohead);
 }
 
+static void stats_fn(struct cgit_context *ctx)
+{
+	if (ctx->repo->enable_stats)
+		cgit_show_stats(ctx);
+	else
+		cgit_print_error("Stats disabled for this repo");
+}
+
 static void summary_fn(struct cgit_context *ctx)
 {
 	cgit_print_summary();
@@ -145,6 +154,7 @@ struct cgit_cmd *cgit_get_cmd(struct cgit_context *ctx)
 		def_cmd(refs, 1, 1),
 		def_cmd(repolist, 0, 0),
 		def_cmd(snapshot, 1, 0),
+		def_cmd(stats, 1, 1),
 		def_cmd(summary, 1, 1),
 		def_cmd(tag, 1, 1),
 		def_cmd(tree, 1, 1),