Update UniformDistinct.java

Refactored. Added comparable and pre-allocated shufflers. 

(Really need to refactor the other example algorithms to re-use a pre-allocated array. Which is what you would do if you needed to run this often enough that time mattered.)

Output from running on my latop.

reporting speed Max: 1048576
              hash  hash/neg    hybrid reservoir      tree   shuffle  shuffle2
  4096        0.11      0.12      0.14      0.01      0.17      0.04      4.60
  2048        3.09      4.49      4.71      0.02      0.72      0.12      4.36
  1024        5.40      5.33      0.67      0.04      1.80      0.27      8.41
   512        4.53      4.81      9.84      0.09      1.71      0.52      8.26
   256        5.92      5.75     15.37      0.19      4.05      1.07     11.40
   128        5.57      5.64     20.66      0.36      4.59      2.08     11.61
    64        4.55      4.52     21.56      0.71      3.64      3.93     19.17
    32        5.09      5.05     25.75      1.34      3.71      7.59     18.92
    16        4.70      4.83     27.15      2.40      3.02      9.93     21.46
     8        3.25      3.58     27.36      4.05      2.25     16.87     22.55
     4        2.59      2.49     25.08      6.34      1.43     20.52     22.06
     2        2.03      1.80     21.04     10.15      0.88     23.17     24.32
  4096        4.89      6.50      5.89      0.01      6.62      0.08      7.69
  2048        5.53      6.66      6.65      0.02      6.55      0.04      7.16
  1024        5.53      6.35      9.30      0.05      6.08      0.33      8.45
   512        5.56      5.75     13.76      0.09      5.27      0.66      7.63
   256        5.92      6.02     14.85      0.18      4.94      1.27     10.26
   128        5.66      5.61     19.66      0.36      4.57      2.38     14.29
    64        5.18      5.21     22.18      0.69      4.17      4.32     15.62
    32        5.24      5.13     25.91      1.32      3.75      7.54     20.27
    16        4.66      4.86     27.55      2.40      3.06     11.64     22.08
     8        3.59      3.60     26.75      4.06      2.19     10.68     23.25
     4        2.60      2.55     25.67      6.46      1.41     20.59     23.75
     2        2.02      2.03     20.62     10.20      0.88     23.08     22.53
  4096        5.27      6.14      6.07      0.01      6.33      0.08      7.59
  2048        5.81      6.57      6.10      0.02      6.52      0.17      7.83
  1024        5.66      5.97      9.07      0.05      6.14      0.31      7.95
   512        5.41      5.77     12.76      0.09      5.64      0.63      9.07
   256        5.96      5.67     17.20      0.19      4.97      1.24     10.99
   128        5.67      5.71     19.72      0.37      4.59      2.40     13.92
    64        5.44      5.56     22.67      0.71      4.22      4.33     17.66
    32        5.23      5.12     25.87      1.34      3.78      7.65     20.34
    16        4.80      4.88     27.01      2.30      3.20     12.43     22.07
     8        3.47      3.47     27.39      4.08      2.26     17.15     22.83
     4        2.61      2.60     24.89      6.00      1.38     20.61     22.57
     2        2.02      2.01     21.17     10.44      0.89     22.75     24.24
reporting speed Max: 65536
              hash  hash/neg    hybrid reservoir      tree   shuffle  shuffle2
  4096        2.65      3.52      3.51      0.01      3.27      0.13      7.61
  2048        3.85      4.51      4.36      0.02      5.13      0.24      8.33
  1024        4.86      5.42      8.45      0.05      5.64      0.48      9.06
   512        5.63      6.39     12.71      0.09      6.16      0.92     10.61
   256        6.15      6.74     17.58      0.19      6.10      1.72     13.37
   128        6.35      6.47     21.54      0.37      6.54      2.71     13.24
    64        5.96      5.92     22.18      0.72      6.08      7.46     22.76
    32        5.73      6.21     28.35      1.39      5.28     11.21     28.63
    16        5.72      6.02     29.08      2.55      4.97     15.65     32.50
     8        5.47      5.98     27.70      4.47      4.38     26.13     37.07
     4        5.71      5.72     26.56      7.41      3.78     30.53     37.07
     2        5.44      5.57     22.86     12.21      2.79     34.75     38.94
  4096        2.58      3.28      3.35      0.01      3.46      0.13      8.30
  2048        3.83      4.25      4.47      0.02      4.98      0.26      6.21
  1024        4.87      5.37      8.60      0.05      6.02      0.47      8.38
   512        5.63      6.45     13.12      0.09      6.70      0.86     10.53
   256        6.08      6.27     16.36      0.18      6.67      1.77     13.61
   128        6.32      6.36     21.36      0.37      6.52      3.25     12.45
    64        5.79      5.90     23.19      0.71      5.68      7.19     22.98
    32        5.92      6.29     28.25      1.38      5.42     11.66     29.27
    16        5.40      5.56     25.90      2.58      4.85     17.15     31.54
     8        5.73      5.78     27.23      4.45      4.24     27.44     36.95
     4        5.51      5.69     28.63      7.40      3.69     32.48     38.29
     2        5.46      5.54     22.98     12.28      2.91     36.12     38.51
  4096        2.92      3.68      3.70      0.01      3.64      0.12      9.24
  2048        4.57      5.04      5.08      0.02      4.90      0.26      8.01
  1024        5.45      5.84      8.74      0.05      6.22      0.50      9.15
   512        5.99      6.06     13.07      0.09      6.44      1.07     10.31
   256        6.44      7.07     17.72      0.19      6.21      1.99     13.03
   128        6.62      6.93     21.50      0.37      6.52      3.40     15.55
    64        6.51      6.30     22.45      0.73      6.01      6.12     20.40
    32        6.03      6.32     28.30      1.39      5.50      8.80     23.60
    16        5.72      6.17     29.97      2.59      4.76     16.71     32.88
     8        5.88      5.98     27.62      4.54      4.03     27.08     37.26
     4        5.79      5.89     26.89      7.46      3.59     31.67     38.46
     2        5.57      5.61     22.94     12.10      2.91     36.02     38.44