all: Using clang-modernizer to push the C++11 change even further.

Invoked using  -add-override -pass-by-value -use-nullptr -loop-convert
game: Rather than iterating through slots, iterate through fakeplayers in the outer loop in !deletefake
all: Don't use using namespace std in header files.
game: Fix compilation broken a few commits ago.
fileutil: Fix a include line that was before the header guard.