Explore dictionary based pairing function

[fernando-aristizabal]

Explore alternative pairing functions such as dictionary based pairing function.

Related to #24 and #25.

Current behavior

• Only supported pairing functions for categorical data types is cantor and szudzik.

Expected behavior

• Explore alternative pairing function based on dictionary of pairing and expected output such as:

  {
  (c0, b0) : a0, 
  (c0, b1) : a1, 
  (c1, b0) : a2, 
  (c1, b1) : a3, 
  }

• where cX represents a unique value in candidate map, bX unique value in benchmark map, and aX unique value in agreement map.

• This should be a numba vectorized/jit function for performance.

[fernando-aristizabal]

Pairing dict functionality is currently being supported in pairing_dict branch.