make FiberTrace::extractFromProfile complain about NaNs or to deal with them

Currently FiberTrace::extractFromProfile crashes with the message CFits::GCF: ERROR: a too large, ITMAX too small in GCF if NaN s are present in the image, as can happen after the ISR task if the pixels are saturated (maybe Cosmics, too?). Please make the error message more telling, check for Nan s before running the procedure, and make it complain about or fix the problem. Originally the procedure ignored pixels which were masked as 0 while 1 meant a good pixel. I'm not sure how much of that is left.
CFits:: is definitely a remnant from old times and should be replaced with the actual namespace . In general all the debug messages
{{ #ifdef _DEBUG_EXTRACTFROMPROFILE__
cout << "message << endl;
#endif }}
should be replaced with LSST::log messages, but this also part of ticket PIPE2D-165.