fix for ticket #281: Different encoder log on Windows and Linux

Refactor AlfCovariance::getClipMax loop:

This refactoring solve the issue with VS2017 in Release mode, where test "if (E[clip_max[k]][0][k][l] != E[clip_max[k]+1][0][k][l])" was sometime true when it should have been false (noticed with clip_max[k] == 1, i.e. during second iteration of while loop).

Some alternative tries: casting E[][][][] in long long, using std::abs(a-b) < 1, or using std::abs(a-b) < std::numeric_limits::epsilon() failed to solve the issue.

Note: no analysis of the generated assembly has been performed to really understand the problem

Should close #281