Remove "using namespace std"-s

[msoos]

Code has a couple of "using namespace std". As you might imagine ts makes the code littered with "max" and other stuff that is really hard to spot (is it define? C func? etc) Takes 15min to remove, I did that for my fork, but can't merge. I would like to do it, but elbow broken so probably not a good moment to type a lot :)

I am personally fine with e.g. "using std::vector" but importing the whole namespace is just asking for trouble I think.

[msoos]

OK, this has been achieved.