algs: introduce bmssp to find the shortest paths

[mrForza]

What should be implemented:

1. BMSSP algorithm (findPivots, baseCase, bmsspCase)
2. Block heap (get, pull, insert, batchPrepend, delete, split)
3. Red-black tree (insert, delete, search)
4. Unit tests for BMSSP algorithm
5. Unit tests for Block heap
6. Unit tests for Red-black tree
7. Integration tests for BMSSP algorithm (on different graphs in manual mode)