Use unlifted Array# for TArray

[konsumlamm]

Closes #13.

I copied the code for Array for the most part. The new newArray doesn't separate the construction of the TVar#s and the construction of the Array# (unlike the old version), I'm not sure if that's a problem.

The benchmarks show that TBQueue gets a bit faster with this change.

Benchmark results

All
  concurrent spsc
    Chan:               OK (0.95s)
      317  ms ± 7.5 ms
    TChan:              OK (2.85s)
      189  ms ±  15 ms
    TQueue:             OK (34.34s)
      127  ms ± 9.7 ms
    TBQueue (unlifted): OK (0.48s)
      160  ms ±  15 ms
    TBQueue:            OK (0.62s)
      206  ms ±  19 ms
  concurrent mpmc
    Chan:               OK (35.09s)
      11.698 s ±  19 ms
    TChan:              OK (5.04s)
      734  ms ±  30 ms
    TQueue:             OK (1.63s)
      545  ms ±  45 ms
    TBQueue (unlifted): OK (17.37s)
      1.190 s ±  26 ms
    TBQueue:            OK (3.93s)
      1.300 s ± 123 ms
  bulk
    Chan:               OK (6.68s)
      443  ms ±  23 ms
    TChan:              OK (3.25s)
      462  ms ±  19 ms
    TQueue:             OK (1.00s)
      336  ms ±  19 ms
  burst
    Chan:               OK (2.92s)
      206  ms ±  18 ms
    TChan:              OK (3.50s)
      238  ms ±  11 ms
    TQueue:             OK (0.52s)
      177  ms ± 7.1 ms
    TBQueue (unlifted): OK (0.77s)
      257  ms ±  13 ms
    TBQueue:            OK (0.78s)
      263  ms ± 4.2 ms

[bgamari]

Can you add entries to the CHANGELOG describing this and your previous changes?