Inserts a new key and value into a Tree similar to insert.
The difference is that if the key already exists in the Tree, it gets replaced by the new
key. If you supplied a value_destroy_func when creating the Tree, the old value is
freed using that function. If you supplied a key_destroy_func when creating the Tree
, the old key is freed using that function.
The tree is automatically 'balanced' as new key/value pairs are added, so that the distance from the root to every leaf is as small as possible.
| this |
a Tree |
| key |
the key to insert |
| value |
the value corresponding to the key |