RealRandomStream::GetNext() must return backoff values for DCF in the range
[0..CW] with uniform probability distribution.

A quick test showed that this is not the case. See counts of some values pulled
from GetNext(0,15):

0=4786 1=9297 2=9426 3=9365 4=9283 5=9335 6=9323 7=9365 8=9312 9=9400 10=9165
11=9482 12=9236 13=9178 14=9429 15=4618 16=0 17=0 

0 and 15 are only half as probable, because round yields 0 for 0-0.5 and 1 for
0.5-1.5.

Created UniformVariable::GetInteger(min,max).

The code works if UniformVariable::GetValue(min,max) never returns max. Is this
absolutely positively the case?

All regressions using DCF are messed up.