Enable BTE to work in Threading environment

Update:

Enable BTE to work in single-threaded or multi-threaded environment.

Update Reasoner Std API Output

Features added:

1. Add source node in the node_binding section of the reasoner output

2. Remove duplicate curie prefix when representing a node (e.g. PR:PR:000012 -> PR:000012)

First release of BTE

Features:
predict (Find the connection between a specific bio-entity and other classes of bio-entities through some intermediate bio-entities)
explain (Find the connection between a specific bio-entity and another bio-entity through some intermediate bio-entities)
hint (Find the right bio-entity based on user input, e.g. gene name, disease name)