addressof is part of <memory>
basic_string is in <string>
fix for: template argument for template template parameter must be a class template or type alias template
needed for std::vector
stub. CreateStandardAlert is dead
move messagebox and SDLMain to platform_objects
needed for std::abs
message is constant
Revert "stub. CreateStandardAlert is dead"

This reverts commit f8761b0d11d8bb842339734ae14d22b36f7b6c57.
use NSAlert for cocoa. Carbon support totally deprecated
Merge branch 'btb/osx-fixes' into unification/master

Merge Mac OS X specific fixes from btb.  The Windows and Linux builds
are unaffected.  The OS X changes look sane, but cannot be tested here.

Changes not specific to OS X were previously committed separately.

Requested by btb: https://github.com/dxx-rebirth/dxx-rebirth/pull/12
For Darwin, code expects SDL_mixer to be in the framework path. Use that here too.