Fix build with ICC 14 + gcc 4.4 system headers (default from SLC6.5) and C++11 enabled.

ICC 14/15 + GCC 4.8/4.9 headers still works fine after applying the patch.

The problem with the gcc 4.4 headers is that "std::isnan" and the C99 macro isnan()
clashed, as we had a "using namespace std" statement in several headers, leading to
an ambiguity. The compiler can't know which we one we want to use.

The straightforward fix is to remove the "using namespace std" statement, and only
selectively import all needed classes from STL namespace (we could also prefix std::
everywhere where it's needed, though that would require much more code changes).

Verified compilation using build_all on SLC6.5 (pcamsphi0).
put UBegin after trfitffkey.init()
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