Add fast CRC-24 implementation

[vanitasvitae]

The default CRC-24 implementation follows RFC4880, which proposes the use of an iterative algorithm. Mimicking a feedback shift register in software is inefficient.

In 'Computation of Cyclic Redundancy Checks via Table Look-Up' Dilip V. Sarwate proposes the use of lookup tables to speed up computation.

This PR implements such table lookup. By calling CRC24.setUseFastImplementation(true), the user can choose to use the fast implementation instead of the traditional one.

The fast algorithm can process 200mb of data in 3.6 seconds, compared to the iterative one which takes 4.9 seconds for the same data.