…or Byte and UInt16 data types

re-use the optimizations of ComputeStatistics(), using SSE2 when available

Before:
```
$ python perftests/computeminmax.py
testByte(): 8.776
testUInt16(): 7.174
testInt16(): 8.210
testFloat32(): 7.846
testFloat64(): 9.407
```

After:
```
$ python perftests/computeminmax.py
testByte(): 0.316
testUInt16(): 0.779
testInt16(): 2.863
testFloat32(): 6.993
testFloat64(): 8.078
```

To be compared with timings of ComputeStatistics():
```
$ python ../perftests/computestatistics.py
testByte(): 0.483
testUInt16(): 1.262
testInt16(): 28.417
testFloat32(): 29.075
testFloat64(): 30.382
```