Fix median computation

[spfetsch]

Existing median implementation assumed a given list of samples was sorted, but
the callers did not sort. Added a sort utility function and sorted the samples
before each use of the median function.

[kamrik]

Oops, that's an important bug. Thanks!
I'll go with copy + sort inside the median function rather than sorting each time before. Speed is not very important here since we never use the median on large arrays. But printing the lists in the original order into the log is important because one might want to check the numbers against earlier verbose sections of the log per event.