Alter GC settings to speed up `Inventory` loads?

[bskinn]

Per Python Bytes Episode 264, GC gets triggered after 700 non-transient memory allocations.

Thus, given that each, e.g., DataObjStr object has a reference cycle within itself (dos.as_bytes.as_str), every ~350 items in an objects.inv will trigger a GC, which is likely useless since the Inventory will want all of those objects in a durable fashion.

Performance details may change if #216 happens.