added Table.update_ids method

@wasade or @ElDeveloper, can one of you review this one? I haven't contributed to biom in a while - let me know if I'm doing anything wrong. The codebase is looking really nice, btw! 
ah, sorry, mislooking. here:

```python
new_id = id_map.get(old_id, old_id)
if strict and new_id is old_id: # same object, not just equality
    raise TableException(...)
updated_ids[idx] = new_id
```