Group related objects when in chunked mode

[Ldp]

When doing large uploads in chunked mode, every chunk is constrain-checked and committed to OSM as it's finished. It still sticks to all nodes before ways before relations. This introduced some things:

• Nodes are visible in OSM long before the chunk with the accompanying ways is committed. You run the risk that someone else deletes/modifies a node before the way appears in the db.
• I believe it was mentioned that server-side constraint checking is a bit faster if a way and its nodes are in the same osmChange.

Prevention of the first issue is, in my eyes, more important than sticking to the exact chunk size, if that would simplify calculations.