Updated Unitary calculator following new code generation style.

[MichaelBroughton]

Updates unitary calculator to use the same style of code in the rest of the library. Hopefully when #227 is resolved, support for unitary calculator can be included more long term :). This is the first step in resolving #263 .

[95-martin-orion]

Looks good modulo some variable names. Is my understanding correct that the changes between simulator_basic and this code are due to manipulating a vector vs. the unitary matrix?

[MichaelBroughton]

Is my understanding correct that the changes between simulator_basic and this code are due to manipulating a vector vs. the unitary matrix?

Yes. The unitary calculator is just like the state vector simulators with two major changes:

1. Larger underlying array (grows like 2^n * 2^n instead of 2^n)
2. The indexing routines and gate application logic have to account for the row and column when applying the gate instead of just the one long row (or column) that is done in the state vector simulator.