Add atom-support

This enables a page which generates atom feeds for the current branch and
path, heavily inspired by the atom-support in gitweb.

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

cmd.c

@@ -10,6 +10,7 @@
 #include "cmd.h"
 #include "cache.h"
 #include "ui-shared.h"
+#include "ui-atom.h"
 #include "ui-blob.h"
 #include "ui-commit.h"
 #include "ui-diff.h"
@@ -22,6 +23,11 @@
 #include "ui-tag.h"
 #include "ui-tree.h"
 
+static void atom_fn(struct cgit_context *ctx)
+{
+	cgit_print_atom(ctx->qry.head, ctx->qry.path, 10);
+}
+
 static void about_fn(struct cgit_context *ctx)
 {
 	if (ctx->repo)
@@ -102,6 +108,7 @@ static void tree_fn(struct cgit_context *ctx)
 struct cgit_cmd *cgit_get_cmd(struct cgit_context *ctx)
 {
 	static struct cgit_cmd cmds[] = {
+		def_cmd(atom, 1, 0),
 		def_cmd(about, 0, 1),
 		def_cmd(blob, 1, 0),
 		def_cmd(commit, 1, 1),