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>

ui-atom.h

@@ -0,0 +1,6 @@
+#ifndef UI_ATOM_H
+#define UI_ATOM_H
+
+extern void cgit_print_atom(char *tip, char *path, int max_count);
+
+#endif