Fix coding style of latest feature branch merge

Fix coding style of latest feature branch merge

* src/itree.c (interval_stack_ensure_space)
(interval_stack_push_flagged, struct itree_iterator)
(struct check_subtree_result, check_subtree, check_tree)
(itree_newlimit, interval_tree_inherit_offset)
(interval_tree_propagate_limit, itree_node_init, itree_node_begin)
(itree_node_end, itree_create, interval_tree_rotate_left)
(interval_tree_rotate_right, interval_tree_insert_fix)
(interval_tree_insert, itree_insert, itree_node_set_region)
(interval_tree_contains, interval_tree_subtree_min)
(interval_tree_remove_fix, interval_tree_replace_child)
(interval_tree_transplant, itree_remove, itree_iterator_start)
(itree_insert_gap, itree_delete_gap, interval_node_intersects)
(itree_iterator_next, itree_iterator_narrow): Tabify.  Fix
comment and code coding style.