utility/ptr: Use std::nullptr_t instead of nullptr_t

nullptr_t is not declared when building with Clang/libc++
client: Use boost::filesystem when building with Clang
ascii: include <cmath>

We use std::pow, which is declared in <cmath>
server/player: include <string>

We use string in this module, and Clang complains if we don't
include <string>
utility/log: Strip out all winapi code
When not passed any arguments, just print out characters.

Signed-off-by: retep998 <retep998@verizon.net>
Merge remote-tracking branch 'snake/linux'
Fixed warning caused by pull request.

Signed-off-by: retep998 <retep998@verizon.net>