Encapsulate Call within the client pool library, so we don't have to expose the clients. Also, write tests for conn module.

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.

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.

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.