Compactification can now optionally create a new module with much smaller sum types

[Krastanov]

The sumtype will contain only the gates that have been seen in the given circuit.

Benchmarks:

using BenchmarkTools
using QuantumClifford

function x_diag_circuit_noisy_measurement(csize)
    circuit = []
    for i in 1:csize
        push!(circuit, PauliError(i, 0.1))
        push!(circuit, sHadamard(i))
        push!(circuit, sCNOT(i, csize+1))
        push!(circuit, sMZ(csize+1,i))
        push!(circuit, ClassicalXOR(1:(i%6+2),i))
    end
    return circuit
end

@benchmark pftrajectories(state,circuit) setup=(state=PauliFrame(1000, 1001, 1001); circuit=x_diag_circuit_noisy_measurement(1000)) evals=1

BenchmarkTools.Trial: 1190 samples with 1 evaluation.
 Range (min … max):  3.341 ms …  4.404 ms  ┊ GC (min … max): 0.00% … 0.00%
 Time  (median):     3.373 ms              ┊ GC (median):    0.00%
 Time  (mean ± σ):   3.383 ms ± 50.728 μs  ┊ GC (mean ± σ):  0.00% ± 0.00%

     ▁▆▄▄▄▄▇█▄▂ ▂▄
  ▃▄▆██████████████▆▆▆▆▅▆▅▅▄▄▄▃▃▄▃▃▂▃▂▂▃▂▃▂▁▁▁▂▂▁▁▁▁▁▁▁▁▁▂▁▂ ▄
  3.34 ms        Histogram: frequency by time        3.51 ms <

 Memory estimate: 281.25 KiB, allocs estimate: 6000.

@benchmark pftrajectories(state,circuit) setup=(state=PauliFrame(1000, 1001, 1001); circuit=compactify_circuit(x_diag_circuit_noisy_measurement(1000); subspecialize=false)) evals=1

BenchmarkTools.Trial: 1049 samples with 1 evaluation.
 Range (min … max):  3.297 ms …  3.783 ms  ┊ GC (min … max): 0.00% … 0.00%
 Time  (median):     3.326 ms              ┊ GC (median):    0.00%
 Time  (mean ± σ):   3.342 ms ± 57.815 μs  ┊ GC (mean ± σ):  0.00% ± 0.00%

   ▆█▇▇█▇▅▅▄▂▄▁▁▁                                            ▁
  ▇██████████████▇▇▆▅▆▇▆▆▇▄▄▄▅▄▄▆▆▄▇▅▆▄▇▇▆▆▁▅▄▅▆▁▁▁▁▆▁▄▄▁▄▁▆ █
  3.3 ms       Histogram: log(frequency) by time      3.6 ms <

 Memory estimate: 48 bytes, allocs estimate: 1.

circuit=compactify_circuit(x_diag_circuit_noisy_measurement(1000); subspecialize=false)
state=PauliFrame(1000, 1001, 1001)
@benchmark pftrajectories($state,$circuit)

BenchmarkTools.Trial: 1494 samples with 1 evaluation.
 Range (min … max):  3.189 ms …  3.620 ms  ┊ GC (min … max): 0.00% … 0.00%
 Time  (median):     3.353 ms              ┊ GC (median):    0.00%
 Time  (mean ± σ):   3.345 ms ± 48.549 μs  ┊ GC (mean ± σ):  0.00% ± 0.00%

                                 ▂▆▄█▆▇▄▂▁
  ▃▂▂▃▃▃▃▃▃▄▃▃▃▃▃▂▂▃▂▂▂▁▂▂▁▁▁▂▃▅▆██████████▅▄▃▃▂▂▂▂▂▂▂▂▂▂▂▂▂ ▃
  3.19 ms        Histogram: frequency by time        3.46 ms <

 Memory estimate: 0 bytes, allocs estimate: 0.

circuit=compactify_circuit(x_diag_circuit_noisy_measurement(1000); subspecialize=true)
state=PauliFrame(1000, 1001, 1001)
@benchmark pftrajectories($state,$circuit)

BenchmarkTools.Trial: 1563 samples with 1 evaluation.
 Range (min … max):  3.179 ms …  3.358 ms  ┊ GC (min … max): 0.00% … 0.00%
 Time  (median):     3.196 ms              ┊ GC (median):    0.00%
 Time  (mean ± σ):   3.197 ms ± 11.439 μs  ┊ GC (mean ± σ):  0.00% ± 0.00%

          ▁▄▇█▇▄▁
  ▂▁▂▂▃▃▄▇███████▆▄▃▄▃▃▂▂▂▂▂▂▂▂▂▂▂▂▂▁▂▁▁▁▁▁▁▁▁▁▁▁▂▂▁▁▁▁▂▂▂▂▂ ▃
  3.18 ms        Histogram: frequency by time        3.26 ms <

 Memory estimate: 0 bytes, allocs estimate: 0.