Remove gql module's dependency on query. Make it the other way round. GraphQL query string, now gets converted into query.SubGraph as an additional step run via query.ToSubGraph.

Use cache for streaming entries instead of opening files for each posting list. Use iterator instead of channel while streaming entries.

Loads of fixes and tweaks to make data loading work. Largely, the system is really fast in inserting data, but memory becomes a problem. So, running continuous memory checks, and if the db exceeds set memory, then stopping in world in batch load mode to deal with it first. In server mode, same code runs but without stopping the world.

Handle reading rdf data from files. Use underscores for uid and xid, keeping it in sync with internal usage. Output uids as hex.

Make list matrix work, yeah! This would serialize uids for the next query, which would then again return a matrix, so on and so forth.

BREAKING change: convert to JSON. Given we're not tracking uids for each query uid, this will cause problems for the result. So, have to re-structure stuff here.

Modified posting package to include a way to query multiple posting lists for a given attribute. Introduce a new task.fbs which would be used for query and result encoding.