Use client's session to set POC for test, now that we have the capability to do that.
Use a middleware to set the current POC one time per request, and avoid having to look up the stack for the current request in 'get_current_poc'.
Fetch all overrides for a block at one time.
Speed up the lineage computation by doing some caching.
Unused import.
Get field overrides once per user per block.
Streamline configuration.
Fix poc config tuples
