Code review comment for lp:~p12/kicad/remove-uses-namespace-std

The negotiated result was that we are to add these lines to the Coding Standards document:

  The project should never use 'using namespace ...' in a header file, but using
  it in a *.cpp file is OK, according to the author of the *.cpp file's preference.
  If it occurs in a *.cpp file, it must occur after any #include statements.

(Wayne agreed to do that.)

Then I consulted authors/developers who have made use of 'using namespace' in *.cpp files, which is still legal, to find out what they were willing to give up. The applied patch is a result of this process, and it is a subset of the original request.