ui-tree: use render filters to display content

This allows applying filters to files in the repository, for example to
render Markdown or AsciiDoc as HTML.

Signed-off-by: John Keeping <john@keeping.me.uk>
diff --git a/ui-tree.h b/ui-tree.h
index bbd34e3..a0fc8e2 100644
--- a/ui-tree.h
+++ b/ui-tree.h
@@ -1,6 +1,6 @@
 #ifndef UI_TREE_H
 #define UI_TREE_H
 
-extern void cgit_print_tree(const char *rev, char *path);
+extern void cgit_print_tree(const char *rev, char *path, bool use_render);
 
 #endif /* UI_TREE_H */